CF99, Cardiff
Mowing
When you can next cut it, and the best slot this weekend.
Best weekend slot
Nothing doing
Verdict: Not worth it
0.4mm of rain falling.
Today afternoon is your first decent window.
Next mow
Today 2pm–3pm
Verdict: Good to go, 65% chance it holds
grass slightly damp — rain earlier that day
- Worth watching: Ground still soft. 46mm rain over the last week, medium (loam) soil. A mower will mark it, and a ride-on will rut it. More
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.
Monday 19 October: 2 hours worth using. 6pm–7pm — grass slightly damp — 2 hours after the rain
Monday 19 October, hour by hour 5am 6am 7am 8am 9am 10am 11am midday 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm Chance — — — — — <5% <5% <5% <5% 65% 55% 60% 65% 90% — — Verdict Already gone Already gone Already gone Already gone Already gone Forget it Forget it Forget it Forget it Good to go Touch and go Touch and go Touch and go Prime time dark dark Rainchance · · · · · 12% 4% 7% 3% 20% 10% 25% 0% 4% 3% 0% Rainmm · · · · · — — — — 0.1 — 0.1 — — — — Grass · · · · · soaked soaked soaked soaked wet wet damp damp damp dry dry Ground · · · · · firm firm firm firm firm firm firm firm firm firm firm Temp · · · · · 10° 11° 12° 13° 13° 12° 13° 13° 13° 13° 13° Windkm/h · · · · · 17 19 18 17 17 18 10 6 21 18 17 Daylight · · · · · ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ — — Growth: barely growing (growth potential 0.18). 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 October · best slot6pm–7pmReasonably confident
6pm–7pm — grass slightly damp — 2 hours after the rain
90% prime time. About 1 run in 10 found the grass too wet.
Also mowable today: 2pm–3pm (65%)
Limiting factor:grass wetness
Tuesday 20 October: no hours worth using. No — 0.9mm of rain falling.
Tuesday 20 October, hour by hour 5am 6am 7am 8am 9am 10am 11am midday 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm Chance — — — 30% 30% 25% 25% 25% 25% 25% 25% 25% 30% 30% — — Verdict dark dark dark Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it dark dark Rainchance 41% 46% 43% 51% 46% 49% 44% 36% 27% 23% 18% 13% 9% 4% 11% 4% Rainmm 0.3 0.4 0.3 0.5 0.4 0.6 0.4 0.2 0.2 0.2 0.1 0.1 — — 0.1 — Grass wet wet wet wet wet soaked soaked soaked soaked wet wet wet wet wet wet soaked Ground firm firm firm firm firm firm firm firm firm firm firm firm firm firm firm firm Temp 10° 10° 10° 10° 10° 10° 10° 10° 11° 11° 11° 11° 12° 11° 10° 9° Windkm/h 10 7 7 7 6 8 13 14 12 13 14 9 9 6 4 1 Daylight — — — ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ — — Growth: barely growing (growth potential 0.14). 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 — 0.9mm of rain falling.
30% pushing it. About 2 runs in 3 found the grass too wet.
Limiting factor:grass wetness
Wednesday 21 October: nothing to cut. Nothing to cut — the grass is barely growing (growth potential 0.10).
Wednesday 21 October, hour by hour 5am 6am 7am 8am 9am 10am 11am midday 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm Chance — — — <5% <5% <5% <5% <5% <5% <5% 25% 40% 25% 30% — — Verdict nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing nothing to cut — the grass is barely growing Rainchance 30% 33% 37% 24% 29% 23% 25% 18% 18% 24% 24% 20% 32% 33% 38% 24% Rainmm 0.5 0.4 0.4 0.2 0.3 0.1 0.2 0.2 0.3 0.2 0.3 0.2 0.3 0.2 0.2 0.3 Grass soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked wet wet wet soaked soaked Ground firm bog bog soft soft soft soft soft soft soft soft soft soft soft soft firm Temp 12° 11° 11° 10° 10° 10° 10° 9° 9° 9° 9° 9° 9° 9° 9° 8° Windkm/h 16 16 12 13 23 20 22 30 34 32 26 21 19 18 17 13 Daylight — — — ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ — — Growth: barely growing (growth potential 0.10). 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.
Wednesday 21 OctoberReasonably confident
Nothing to cut — the grass is barely growing (growth potential 0.10).
40% 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
Thursday 22 October: no hours worth using. No — 0.2mm of rain falling.
Thursday 22 October, hour by hour 5am 6am 7am 8am 9am 10am 11am midday 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm Chance — — — <5% <5% <5% <5% <5% <5% <5% <5% <5% <5% <5% — — Verdict dark dark dark Forget it Forget it Forget it Forget it Forget it Forget it Forget it Forget it Forget it Forget it Forget it dark dark Rainchance 39% 32% 38% 26% 26% 25% 31% 25% 25% 49% 45% 65% 57% 66% 65% 65% Rainmm 0.4 0.3 0.4 0.1 0.1 0.1 0.1 0.1 0.1 0.3 0.3 0.4 0.5 0.6 0.7 1.1 Grass soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked Ground soft soft soft soft soft soft soft soft soft soft soft soft soft soft soft soft Temp 6° 5° 4° 5° 7° 8° 9° 11° 12° 12° 13° 13° 12° 11° 11° 11° Windkm/h 8 5 4 5 6 6 6 6 6 8 9 11 13 14 17 21 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.
Thursday 22 OctoberConfident
No — 0.2mm of rain falling.
<5% forget it. Almost every run found the grass too wet.
Limiting factor:grass wetness
Friday 23 October: no hours worth using. No — 0.8mm of rain falling.
Friday 23 October, hour by hour 5am 6am 7am 8am 9am 10am 11am midday 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm Chance — — — <5% <5% <5% <5% <5% <5% 5% 10% 10% 15% 15% — — Verdict dark dark dark ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged Forget it Forget it Forget it Forget it Pushing it dark dark Rainchance 63% 53% 63% 43% 36% 27% 37% 36% 24% 32% 39% 39% 24% 16% 18% 14% Rainmm 0.8 0.8 0.8 0.3 0.5 0.3 0.4 0.4 0.3 0.3 0.4 0.3 0.1 0.2 0.2 0.2 Grass soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked soaked wet wet wet damp damp Ground bog bog bog bog bog bog bog bog bog soggy soggy soggy soggy soggy bog bog Temp 11° 11° 11° 10° 9° 9° 9° 9° 9° 10° 10° 10° 10° 10° 10° 9° Windkm/h 36 40 42 42 42 41 40 39 37 34 31 28 27 27 26 25 Daylight — — — ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ — — Growth: barely growing (growth potential 0.12). 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.
Friday 23 OctoberReasonably confident
No — 0.8mm of rain falling.
15% pushing it. About 2 runs in 3 found the ground too soft.
Limiting factor:ground firmness
Saturday 24 October: no hours worth using. No — 0.5mm of rain falling.
Saturday 24 October, hour by hour 5am 6am 7am 8am 9am 10am 11am midday 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm Chance — — — 35% 30% 30% 30% 35% 30% 25% 20% 20% 20% <5% — — Verdict dark dark dark Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it Pushing it ground waterlogged dark dark Rainchance 11% 13% 9% 4% 18% 6% 21% 14% 20% 22% 20% 22% 25% 22% 24% 27% Rainmm 0.1 0.1 0.1 — 0.4 0.1 0.6 0.9 0.5 1 0.8 0.9 1.1 1.1 1.0 0.5 Grass damp damp damp wet wet wet wet damp wet wet wet wet wet soaked soaked soaked Ground soggy soggy soggy soggy soggy soggy soggy soggy soggy soggy soggy soggy soggy bog bog bog Temp 7° 7° 7° 8° 8° 9° 10° 10° 11° 10° 10° 9° 10° 10° 11° 12° Windkm/h 18 16 14 13 12 11 13 16 19 19 20 20 22 23 25 25 Daylight — — — ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ — — Growth: barely growing (growth potential 0.11). 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.
Saturday 24 OctoberLow confidence this far out
No — 0.5mm of rain falling.
35% pushing it. About 2 runs in 3 found the ground too soft.
Limiting factor:ground firmness
Sunday 25 October: no hours worth using. No — 0.4mm of rain falling.
Sunday 25 October, hour by hour 5am 6am 7am 8am 9am 10am 11am midday 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm Chance — — <5% <5% 5% 10% 10% 10% 10% 20% 10% 20% — — — — Verdict dark dark Forget it Forget it Forget it Forget it Forget it Forget it Forget it Pushing it Forget it Pushing it dark dark dark dark Rainchance 27% 29% 22% 16% 12% 16% 22% 12% 18% 16% 31% 25% 20% 20% 16% 22% Rainmm 0.4 0.3 0.4 0.6 0.1 0.2 0.5 0.4 0.2 0.1 0.4 0.3 0.2 0.2 0.2 0.2 Grass soaked soaked soaked soaked soaked soaked soaked wet wet wet wet wet wet damp damp wet Ground bog bog sodden sodden sodden sodden sodden sodden sodden sodden sodden sodden sodden sodden sodden sodden Temp 16° 16° 16° 16° 16° 16° 15° 15° 14° 14° 13° 13° 12° 12° 12° 11° Windkm/h 26 27 30 34 38 42 45 46 45 43 39 35 32 30 29 28 Daylight — — ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ — — — — Growth: growing slowly (growth potential 0.34). 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 OctoberReasonably confident
No — 0.4mm of rain falling.
20% pushing it. About 2 runs in 3 found the grass too wet.
Limiting factor:grass wetness
Monday 26 October: no hours worth using. No — 0.2mm of rain falling.
Monday 26 October, hour by hour 5am 6am 7am 8am 9am 10am 11am midday 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm Chance — — <5% <5% 5% 5% 10% 15% 10% 15% 20% 20% — — — — Verdict dark dark Forget it Forget it Forget it Forget it Forget it Pushing it Forget it Forget it Pushing it Pushing it dark dark dark dark Rainchance 18% 20% 27% 10% 14% 14% 22% 16% 31% 12% 20% 20% 27% 16% 27% 24% Rainmm 0.3 0.5 0.6 0.3 0.3 0.2 0.4 0.5 0.4 0.2 0.4 0.3 0.5 0.2 0.3 0.7 Grass soaked soaked soaked soaked soaked soaked soaked wet wet wet wet wet wet wet soaked soaked Ground soggy sodden sodden sodden sodden sodden sodden sodden sodden soggy soggy soggy soggy soggy soggy soggy Temp 9° 10° 10° 11° 12° 13° 14° 14° 14° 14° 13° 13° 12° 12° 13° 13° Windkm/h 14 14 13 12 15 21 26 29 29 26 22 17 13 10 10 12 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 26 OctoberReasonably confident
No — 0.2mm of rain falling.
20% pushing it. About 2 runs in 3 found the ground too soft.
Limiting factor:ground firmness
Tuesday 27 October: no hours worth using. No — 0.5mm of rain falling.
Tuesday 27 October, hour by hour 5am 6am 7am 8am 9am 10am 11am midday 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm Chance — — <5% <5% <5% <5% <5% <5% <5% <5% <5% 20% — — — — Verdict dark dark ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged Pushing it dark dark dark dark Rainchance 31% 25% 24% 24% 24% 25% 20% 25% 18% 24% 24% 29% 18% 18% 12% 18% Rainmm 0.4 0.5 0.3 0.4 0.3 0.3 0.3 0.5 0.2 0.3 0.4 0.5 0.3 0.1 0.1 0.2 Grass soaked soaked soaked soaked soaked soaked wet wet wet wet wet wet wet wet wet wet Ground bog bog bog bog bog bog bog bog bog bog bog sodden sodden soggy soggy soggy Temp 15° 15° 15° 15° 15° 15° 14° 14° 14° 14° 14° 13° 13° 13° 13° 12° Windkm/h 21 22 23 26 31 35 39 42 41 40 37 34 31 29 27 25 Daylight — — ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ — — — — Growth: growing slowly (growth potential 0.33). 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 OctoberLow confidence this far out
No — 0.5mm of rain falling.
20% pushing it. About 2 runs in 3 found the grass too wet.
Limiting factor:grass wetness
Wednesday 28 October: no hours worth using. No — 0.5mm of rain falling.
Wednesday 28 October, hour by hour 5am 6am 7am 8am 9am 10am 11am midday 1pm 2pm 3pm 4pm 5pm 6pm 7pm 8pm Chance — — <5% <5% <5% <5% <5% <5% <5% <5% <5% <5% — — — — Verdict dark dark ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged ground waterlogged dark dark dark dark Rainchance 37% 10% 16% 12% 18% 10% 22% 14% 10% 20% 16% 14% 14% 18% 20% 10% Rainmm 0.4 0.1 0.1 0.1 0.3 0.1 0.2 0.2 0.2 0.1 0.2 0.2 0.1 0.2 0.2 0.1 Grass soaked soaked soaked soaked soaked soaked wet wet wet wet wet wet wet wet wet wet Ground soggy soggy bog bog bog bog bog bog bog bog bog bog bog bog bog bog Temp 11° 11° 11° 12° 12° 13° 14° 14° 14° 14° 14° 14° 14° 13° 13° 13° Windkm/h 12 12 13 15 18 21 23 25 26 27 27 27 27 28 28 29 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.
Wednesday 28 OctoberLow confidence this far out
No — 0.5mm of rain falling.
<5% forget it. Almost every run found the grass too wet.
Limiting factor:grass wetness
good to go touch and go dark, frost or snow already goneFainter means fewer forecast runs agree.
Growth
How fast it is growing, and when it will need cutting again.
18%Barely growing
Of the fastest this grass could grow. The turf-industry measure, from today's temperature and day length.
The lawn is barely growing, so it does not need cutting. Leave it — taking leaf off a sward that cannot replace it costs more than it gives.
Held back by both temperature and short days — 10.5 hours of daylight at 11°C.
- Over the next 10 days
- about 7mm 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 CF99, Cardiff
9.8°C50°F
at 6cm — germination depth
Seeding conditions are open — soil is 9.8°C at 6cm and holding above 9°C.
Warming over the next 10 days.
Cross-checks against an independent estimate from air temperature (11.6°C), which agrees to within 1.0°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.
| Species | Soil needed | Days to sprout |
|---|---|---|
| Perennial ryegrasslikely yours | 8°C | 5–10 |
| Red / chewings fescuelikely yours | 8–10°C | 10–14 |
| Tall fescue | 10–12°C | 10–14 |
| Browntop bentColonial bentgrass | 10–12°C | 14–21 |
| Smooth-stalked meadow grassKentucky bluegrass | 12–13°C | 14–28 |
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.
CF99, Cardiff in detail
Soil temperature in CF99, Cardiff is currently 9.8°C at 6cm, and rising about 1.5°C over the next 10 days. 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 9.8°C at 6cm and holding above 9°C.
2 of the next 10 days look workable. The other 8 are held back by wet grass or soft ground. As for the weekend: nothing doing. 0.4mm of rain falling.
The next recommended window in CF99 opens at 6pm on Monday 19 October, because that is when the dew has burnt off — earlier than that and you are cutting wet grass. Underfoot, the ground reads as firm after 9mm rain over the last week, medium (loam) soil.
Save this lawn and we will email you when the windows open.
We already send you the forecast email? Use the same address.
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.