CB1, Cambridge

CB1, Cambridge52.1952, 0.1415from your postcode

Mowing

When you can next cut it, and the best slot this weekend.

Best weekend slot

Sunday 4pm–5pm

Verdict: Good to go, 75% chance it holds

grass damp — wet underfoot, rain falling then

Next mow

Sunday 4pm–5pm

Verdict: Good to go, 75% chance it holds

grass damp — wet underfoot, rain falling then

The next 10 days

Each row is a day, morning on the left. The more solid a block, the more of the forecast runs agree you can mow. Open a day for the hour-by-hour forecast behind it.

  1. Monday 19 October: no hours worth using. No — grass wet, still wet underfoot, rain earlier today.
    Monday 19 October, hour by hour
    5am6am7am8am9am10am11ammidday1pm2pm3pm4pm5pm6pm7pm8pm
    Chance——————<5%<5%<5%<5%<5%<5%<5%———
    VerdictAlready goneAlready goneAlready goneAlready goneAlready goneAlready goneForget itForget itForget itForget itForget itForget itForget itdarkdarkdark
    Rainchance······3%3%2%2%0%2%0%0%0%0%
    Rainmm······——————————
    Grass······soakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoaked
    Ground······firmfirmfirmfirmfirmfirmfirmfirmfirmfirm
    Temp······12°13°13°13°14°14°13°13°12°12°
    Windkm/h······55487109985
    Daylight······✓✓✓✓✓✓✓———

    Growth: growing slowly (growth potential 0.21). Enough to be worth cutting. Growth decides whether a cut is wanted, not how well it will go, so it is not one of the rows above and does not move the chances.Chance is the share of 94 forecast runs — the same weather models re-run from slightly different starting conditions — in which you could have mowed that hour. The rows below it are what those runs expect on average, which is why an hour can look reasonable line by line and still fall short: the chance only counts runs where everything came together at once. Hover any cell for what the runs that ruled it out actually hit.

    Monday 19 OctoberConfident

    No — grass wet, still wet underfoot, rain earlier today.

    <5% forget it. Almost every run found the grass too wet.

    Limiting factor:grass wetness

  2. Tuesday 20 October: no hours worth using. No — 0.1mm of rain falling.
    Tuesday 20 October, hour by hour
    5am6am7am8am9am10am11ammidday1pm2pm3pm4pm5pm6pm7pm8pm
    Chance———10%15%20%30%35%20%25%20%10%5%———
    VerdictdarkdarkdarkForget itPushing itPushing itPushing itPushing itPushing itPushing itPushing itForget itForget itdarkdarkdark
    Rainchance18%18%21%17%32%31%46%41%48%50%52%48%52%36%38%25%
    Rainmm0.10.10.10.10.10.20.30.30.40.50.60.60.50.30.30.1
    Grasssoakedsoakedsoakedsoakedsoakedsoakedwetwetsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoaked
    Groundfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirm
    Temp12°12°12°12°13°13°13°13°13°13°13°13°13°13°12°12°
    Windkm/h1113121213141717161415111091013
    Daylight———✓✓✓✓✓✓✓✓✓✓———

    Growth: growing slowly (growth potential 0.24). Enough to be worth cutting. Growth decides whether a cut is wanted, not how well it will go, so it is not one of the rows above and does not move the chances.Chance is the share of 94 forecast runs — the same weather models re-run from slightly different starting conditions — in which you could have mowed that hour. The rows below it are what those runs expect on average, which is why an hour can look reasonable line by line and still fall short: the chance only counts runs where everything came together at once. Hover any cell for what the runs that ruled it out actually hit.

    Tuesday 20 OctoberLow confidence this far out

    No — 0.1mm of rain falling.

    35% pushing it. About 2 runs in 3 found the grass too wet.

    Limiting factor:grass wetness

  3. Wednesday 21 October: no hours worth using. No — 0.1mm of rain falling.
    Wednesday 21 October, hour by hour
    5am6am7am8am9am10am11ammidday1pm2pm3pm4pm5pm6pm7pm8pm
    Chance———10%10%<5%<5%<5%<5%<5%<5%<5%<5%———
    VerdictdarkdarkdarkForget itForget itForget itForget itForget itForget itForget itForget itForget itForget itdarkdarkdark
    Rainchance7%8%20%18%23%31%31%24%23%29%29%28%35%31%26%28%
    Rainmm——0.10.10.10.20.20.20.30.20.20.20.20.20.20.2
    Grasssoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoaked
    Groundfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirm
    Temp9°9°9°9°10°10°11°11°12°12°13°13°11°10°9°8°
    Windkm/h101112131416181716128816283637
    Daylight———✓✓✓✓✓✓✓✓✓✓———

    Growth: barely growing (growth potential 0.10). Enough to be worth cutting. Growth decides whether a cut is wanted, not how well it will go, so it is not one of the rows above and does not move the chances.Chance is the share of 94 forecast runs — the same weather models re-run from slightly different starting conditions — in which you could have mowed that hour. The rows below it are what those runs expect on average, which is why an hour can look reasonable line by line and still fall short: the chance only counts runs where everything came together at once. Hover any cell for what the runs that ruled it out actually hit.

    Wednesday 21 OctoberConfident

    No — 0.1mm of rain falling.

    10% forget it. Almost every run found the grass too wet.

    Limiting factor:grass wetness

  4. Thursday 22 October: nothing to cut. Nothing to cut — the grass is barely growing (growth potential 0.06). Conditions themselves are fine.
    Thursday 22 October, hour by hour
    5am6am7am8am9am10am11ammidday1pm2pm3pm4pm5pm6pm7pm8pm
    Chance———10%10%10%15%25%85%85%90%90%85%———
    Verdictnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growing
    Rainchance13%9%14%3%4%4%2%2%2%7%5%7%12%10%11%39%
    Rainmm—0.10.1—————————0.1——0.2
    Grasssoakedsoakedsoakedsoakedsoakedsoakedsoakedwetdampdampdrydrydrydrydampdamp
    Groundfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirm
    Temp5°5°5°5°6°7°8°10°11°12°12°12°11°10°9°8°
    Windkm/h1098891012131415141413121112
    Daylight———✓✓✓✓✓✓✓✓✓✓———

    Growth: barely growing (growth potential 0.06). Not enough to be worth cutting, which is why no hour is recommended today whatever the weather does.Chance is the share of 94 forecast runs — the same weather models re-run from slightly different starting conditions — in which you could have mowed that hour. The rows below it are what those runs expect on average, which is why an hour can look reasonable line by line and still fall short: the chance only counts runs where everything came together at once. Hover any cell for what the runs that ruled it out actually hit.

    Thursday 22 OctoberReasonably confident

    Nothing to cut — the grass is barely growing (growth potential 0.06). Conditions themselves are fine.

    90% nothing to cut. About 1 run in 10 found the grass barely growing.

    Nothing to cut. The odds below describe the weather only — growth decides whether a cut is wanted, and it is judged separately.

    Limiting factor:growth

  5. Friday 23 October: nothing to cut. Nothing to cut — the grass is barely growing (growth potential 0.09).
    Friday 23 October, hour by hour
    5am6am7am8am9am10am11ammidday1pm2pm3pm4pm5pm6pm7pm8pm
    Chance———<5%<5%<5%<5%<5%<5%<5%<5%10%25%———
    Verdictnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growing
    Rainchance61%44%50%43%32%36%33%40%29%31%42%27%31%28%27%8%
    Rainmm0.50.40.50.30.20.20.20.40.20.30.30.30.20.20.20.1
    Grasssoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoakedsoaked
    Groundfirmsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoft
    Temp12°11°11°10°10°10°9°9°9°9°9°9°8°6°6°6°
    Windkm/h242422179715283842434443424038
    Daylight———✓✓✓✓✓✓✓✓✓✓———

    Growth: barely growing (growth potential 0.09). Not enough to be worth cutting, which is why no hour is recommended today whatever the weather does.Chance is the share of 94 forecast runs — the same weather models re-run from slightly different starting conditions — in which you could have mowed that hour. The rows below it are what those runs expect on average, which is why an hour can look reasonable line by line and still fall short: the chance only counts runs where everything came together at once. Hover any cell for what the runs that ruled it out actually hit.

    Friday 23 OctoberReasonably confident

    Nothing to cut — the grass is barely growing (growth potential 0.09).

    25% nothing to cut. About 2 runs in 3 found the grass barely growing.

    Nothing to cut. The odds below describe the weather only — growth decides whether a cut is wanted, and it is judged separately.

    Limiting factor:growth

  6. Saturday 24 October: nothing to cut. Nothing to cut — the grass is barely growing (growth potential 0.06). Conditions themselves are fine.
    Saturday 24 October, hour by hour
    5am6am7am8am9am10am11ammidday1pm2pm3pm4pm5pm6pm7pm8pm
    Chance———50%45%55%60%65%70%70%70%65%65%———
    Verdictnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growing
    Rainchance4%5%18%5%5%7%11%10%10%12%14%25%22%25%10%24%
    Rainmm—0.10.2——0.10.10.2—0.20.10.50.30.60.30.5
    Grasswetwetwetwetwetdampdampdampdampdampdampdampdampwetwetwet
    Groundsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftfirmfirmfirmfirm
    Temp6°6°6°6°7°7°9°10°11°11°11°11°10°9°8°8°
    Windkm/h28252322222223232220171413131416
    Daylight———✓✓✓✓✓✓✓✓✓✓———

    Growth: barely growing (growth potential 0.06). Not enough to be worth cutting, which is why no hour is recommended today whatever the weather does.Chance is the share of 94 forecast runs — the same weather models re-run from slightly different starting conditions — in which you could have mowed that hour. The rows below it are what those runs expect on average, which is why an hour can look reasonable line by line and still fall short: the chance only counts runs where everything came together at once. Hover any cell for what the runs that ruled it out actually hit.

    Saturday 24 OctoberLow confidence this far out

    Nothing to cut — the grass is barely growing (growth potential 0.06). Conditions themselves are fine.

    70% nothing to cut. About 1 run in 4 found the grass barely growing.

    Nothing to cut. The odds below describe the weather only — growth decides whether a cut is wanted, and it is judged separately.

    Limiting factor:growth

  7. Sunday 25 October: 1 hour worth using. 4pm–5pm — grass damp — wet underfoot, rain falling then
    Sunday 25 October, hour by hour
    5am6am7am8am9am10am11ammidday1pm2pm3pm4pm5pm6pm7pm8pm
    Chance——15%10%10%15%25%35%60%65%65%75%————
    VerdictdarkdarkForget itForget itForget itPushing itPushing itPushing itTouch and goTouch and goTouch and goGood to godarkdarkdarkdark
    Rainchance18%10%20%12%8%18%18%4%12%12%20%10%16%18%12%12%
    Rainmm0.20.10.10.2—0.10.10.10.10.10.30.10.10.20.10.1
    Grasssoakedsoakedsoakedsoakedsoakedsoakedsoakedwetdampdampdampdampdampdampdampdamp
    Groundsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoft
    Temp14°14°15°16°17°17°18°18°18°17°15°14°13°12°11°11°
    Windkm/h21212224262729303132323232333333
    Daylight——✓✓✓✓✓✓✓✓✓✓————

    Growth: growing slowly (growth potential 0.31). Enough to be worth cutting. Growth decides whether a cut is wanted, not how well it will go, so it is not one of the rows above and does not move the chances.Chance is the share of 94 forecast runs — the same weather models re-run from slightly different starting conditions — in which you could have mowed that hour. The rows below it are what those runs expect on average, which is why an hour can look reasonable line by line and still fall short: the chance only counts runs where everything came together at once. Hover any cell for what the runs that ruled it out actually hit.

    Sunday 25 October · 4pm–5pmLow confidence this far out

    4pm–5pm — grass damp — wet underfoot, rain falling then

    75% good to go. About 1 run in 4 found the grass too wet.

    Limiting factor:grass wetness

  8. Monday 26 October: nothing to cut. Nothing to cut — the grass is barely growing (growth potential 0.08). Conditions themselves are fine.
    Monday 26 October, hour by hour
    5am6am7am8am9am10am11ammidday1pm2pm3pm4pm5pm6pm7pm8pm
    Chance——45%35%35%35%40%40%35%35%35%35%————
    Verdictnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growingnothing to cut — the grass is barely growing
    Rainchance16%10%16%12%14%12%20%10%18%10%14%14%18%10%12%14%
    Rainmm0.30.10.20.10.20.10.20.10.2—0.30.20.30.10.10.2
    Grassdampdampwetwetwetwetwetwetwetwetwetwetwetwetwetwet
    Groundsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoft
    Temp5°6°6°7°8°9°10°10°11°11°11°12°12°12°12°11°
    Windkm/h11111112141618191817151413131212
    Daylight——✓✓✓✓✓✓✓✓✓✓————

    Growth: barely growing (growth potential 0.08). Not enough to be worth cutting, which is why no hour is recommended today whatever the weather does.Chance is the share of 94 forecast runs — the same weather models re-run from slightly different starting conditions — in which you could have mowed that hour. The rows below it are what those runs expect on average, which is why an hour can look reasonable line by line and still fall short: the chance only counts runs where everything came together at once. Hover any cell for what the runs that ruled it out actually hit.

    Monday 26 OctoberLow confidence this far out

    Nothing to cut — the grass is barely growing (growth potential 0.08). Conditions themselves are fine.

    45% nothing to cut. About half the runs found the grass barely growing.

    Nothing to cut. The odds below describe the weather only — growth decides whether a cut is wanted, and it is judged separately.

    Limiting factor:growth

  9. Tuesday 27 October: 3 hours worth using. 1pm–4pm — ground soft in places — 38mm rain over the last week, fine (clay) soil
    Tuesday 27 October, hour by hour
    5am6am7am8am9am10am11ammidday1pm2pm3pm4pm5pm6pm7pm8pm
    Chance——40%35%50%55%55%50%65%70%65%65%————
    VerdictdarkdarkTouch and goPushing itTouch and goTouch and goTouch and goTouch and goGood to goGood to goGood to goTouch and godarkdarkdarkdark
    Rainchance10%12%18%16%10%12%8%24%6%22%16%22%10%12%0%4%
    Rainmm0.10.20.30.10.10.10.20.3—0.10.30.30.10.1—0.1
    Grasswetwetwetwetwetdampdampdampdampdampdampdampdampdampdampdamp
    Groundsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoftsoft
    Temp14°15°15°16°16°16°16°16°16°15°15°14°13°13°12°12°
    Windkm/h27292929292929292828272524232221
    Daylight——✓✓✓✓✓✓✓✓✓✓————

    Growth: growing slowly (growth potential 0.30). Enough to be worth cutting. Growth decides whether a cut is wanted, not how well it will go, so it is not one of the rows above and does not move the chances.Chance is the share of 94 forecast runs — the same weather models re-run from slightly different starting conditions — in which you could have mowed that hour. The rows below it are what those runs expect on average, which is why an hour can look reasonable line by line and still fall short: the chance only counts runs where everything came together at once. Hover any cell for what the runs that ruled it out actually hit.

    Tuesday 27 October · 1pm–4pmLow confidence this far out

    1pm–4pm — ground soft in places — 38mm rain over the last week, fine (clay) soil

    45% touch and go — the chance it holds right through, not the chance at any one hour. About half the runs found the grass too wet.

    Limiting factor:ground firmness

  10. Wednesday 28 October: 6 hours worth using. 11am–5pm — ground firm — 39mm rain over the last week, fine (clay) soil
    Wednesday 28 October, hour by hour
    5am6am7am8am9am10am11ammidday1pm2pm3pm4pm5pm6pm7pm8pm
    Chance——65%65%65%65%70%75%80%85%90%90%————
    VerdictdarkdarkTouch and goTouch and goTouch and goTouch and goGood to goGood to goGood to goPrime timePrime timePrime timedarkdarkdarkdark
    Rainchance12%0%8%0%2%4%2%4%2%0%4%4%0%2%4%4%
    Rainmm0.1—0.1—————————————
    Grassdampdampdampdampdampdampdampdampdampdrydrydrydrydrydrydry
    Groundfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirmfirm
    Temp10°10°10°11°12°12°13°14°14°14°14°13°13°13°13°13°
    Windkm/h15151515161616171819192021222223
    Daylight——✓✓✓✓✓✓✓✓✓✓————

    Growth: growing slowly (growth potential 0.20). Enough to be worth cutting. Growth decides whether a cut is wanted, not how well it will go, so it is not one of the rows above and does not move the chances.Chance is the share of 94 forecast runs — the same weather models re-run from slightly different starting conditions — in which you could have mowed that hour. The rows below it are what those runs expect on average, which is why an hour can look reasonable line by line and still fall short: the chance only counts runs where everything came together at once. Hover any cell for what the runs that ruled it out actually hit.

    Wednesday 28 October · 11am–5pmLow confidence this far out

    11am–5pm — ground firm — 39mm rain over the last week, fine (clay) soil

    65% good to go — the chance it holds right through, not the chance at any one hour. About 1 run in 3 found the grass too wet.

    Limiting factor:ground firmness

good to go touch and go dark, frost or snow already goneFainter means fewer forecast runs agree.

How you feel about mowing

Sensible middle ground.

Petrol or battery. The baseline.

Growth

How fast it is growing, and when it will need cutting again.

21%Growing slowly

Of the fastest this grass could grow. The turf-industry measure, from today's temperature and day length.

Growing slowly — roughly 0.7mm a day. It will not put on enough to need cutting within the next 10 days.

Held back by both temperature and short days — 10.4 hours of daylight at 12°C.

Over the next 10 days
about 6mm of leaf
Next cut due
not within the next ten days

This only knows temperature and day length. Feeding, watering, shade and cutting height all move it, so treat it as a rough guide.

Worked out from the PACE Turf growth potential model and day length —how and why.

Seeding

Soil temperature at germination depth, and when the window opens.

Soil temperature in CB1, Cambridge

11.4°C53°F

at 6cm — germination depth

Seeding conditions are open — soil is 11.4°C at 6cm and holding above 9°C.

Holding steady over the next 10 days.

Cross-checks against an independent estimate from air temperature (11.4°C), which agrees to within 0.1°C.

Almost every UK and Irish lawn is a ryegrass and fescue mix, whether it was sown or turfed. We assume that, and use 9°C as the seeding threshold.

Thresholds for every species

The differences are small. Ryegrass is the quickest off the mark; bluegrass is the slowest and wants the warmest soil. Everything else sits between.

Soil temperature at 6cm for reliable germination. Sources onthe method page.
SpeciesSoil neededDays to sprout
Perennial ryegrasslikely yours8°C5–10
Red / chewings fescuelikely yours8–10°C10–14
Tall fescue10–12°C10–14
Browntop bentColonial bentgrass10–12°C14–21
Smooth-stalked meadow grassKentucky bluegrass12–13°C14–28

Feeding

Why timing decides whether a feed does anything at all.

Coming in the app

Grass takes up nitrogen when it is growing. Feed a lawn that has stopped and most of it washes past the roots — which is why timing beats product choice.

Right now this lawn is not growing fast enough to make much use of a feed.

The app will work out the actual feeding windows for your lawn — along with weed control, scarifying and moss treatment — and tell you when they open without you having to check.

Why timing beats product choice

CB1, Cambridge in detail

Soil temperature in CB1, Cambridge is currently 11.4°C at 6cm, and barely moving. That depth matters because it is where grass seed sits and where roots start working, and it lags air temperature by days — which is why a warm afternoon here tells you very little on its own.

Lawns in this area are typically perennial ryegrass with fescue, which is what most lawns round here are sown with. That blend needs the soil to hold above 9°C before seed germinates reliably. Seeding conditions are open — soil is 11.4°C at 6cm and holding above 9°C.

1 of the next 10 days look workable. The other 9 are held back by wet grass or soft ground. The best weekend slot right now is Sunday 4pm–5pm, on the basis that grass damp — wet underfoot, rain falling then.

The next recommended window in CB1 opens at 4pm on Sunday 25 October, because the rain clears by then. Underfoot, the ground reads as firm after 10mm rain over the last week, fine (clay) soil.

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Chances counted across 94 forecast runs from MOGREPS-UK, 2km and ICON-EU-EPS, 7km and ECMWF IFS ensemble, 25km. Forecast from Open-Meteo, refreshed through the day. Soil temperature is modelled, not measured — how that works and where the thresholds come from.