Lethbridge, Alberta

Best weekend slot

Sunday 10am–9pm

Verdict: Good

no rain since Sunday, ground firm

Next mow

Today 7pm–9pm

Verdict: Good

cool — 25°C

How you feel about mowing

Sensible middle ground.

Petrol or battery. The baseline.

The next 10 days

Column height is how mowable the day is; the lighter band is the best stretch within it. The line is soil temperature at 6cm. It crosses the seeding threshold inside this forecast.

12.5°C — seeding

Soil at 6cm 24.1°C cooling to 0.0°C

Tuesday 1 September: Good. 7pm–9pm — cool — 25°C

Tuesday 1 September · 7pm–9pmConfident

7pm–9pm — cool — 25°C

Good:Grass wetness
Grass dryno rain since Sunday
Good:Ground firmness
Ground firm5mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.86
Marginal:Temperature
Cool25°C
Good:Wind
Wind light5 km/h
Sociable hours
A bit early or late, but finestarts when it stops being antisocial

Limiting factor:temperature

Wednesday 2 September: Good. 8am–9pm — no rain since Sunday, ground firm

Wednesday 2 September · 8am–9pmConfident

8am–9pm — no rain since Sunday, ground firm

Good:Grass wetness
Grass dryno rain since Sunday
Good:Ground firmness
Ground firm5mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.99
Good:Temperature
Temperature15°C
Good:Wind
Wind light4 km/h
Sociable hours
A bit early or late, but finestarts when it stops being antisocial

Limiting factor:none

Thursday 3 September: Good. 8am–9pm — no rain since Sunday, ground firm

Thursday 3 September · 8am–9pmConfident

8am–9pm — no rain since Sunday, ground firm

Good:Grass wetness
Grass dryno rain since Sunday
Good:Ground firmness
Ground firm5mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.61
Good:Temperature
Temperature11°C
Marginal:Wind
Wind light12 km/h
Sociable hours
A bit early or late, but finestarts when it stops being antisocial

Limiting factor:none

Friday 4 September: Good. 8am–9pm — no rain since Sunday, ground firm

Friday 4 September · 8am–9pmConfident

8am–9pm — no rain since Sunday, ground firm

Good:Grass wetness
Grass dryno rain since Sunday
Good:Ground firmness
Ground firm5mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.67
Good:Temperature
Temperature13°C
Good:Wind
Wind light19 km/h
Sociable hours
A bit early or late, but finestarts when it stops being antisocial

Limiting factor:none

Saturday 5 September: Good. 8am–9pm — no rain since Sunday, ground firm

Saturday 5 September · 8am–9pmReasonably confident

8am–9pm — no rain since Sunday, ground firm

Good:Grass wetness
Grass dryno rain since Sunday
Good:Ground firmness
Ground firm5mm rain over the last week
Good:Growth
Growing steadilygrowth potential 0.44
Good:Temperature
Temperature11°C
Good:Wind
Wind light8 km/h
Sociable hours
A bit early or late, but finestarts when it stops being antisocial

Limiting factor:none

Sunday 6 September: Good. 10am–9pm — no rain since Sunday, ground firm

Sunday 6 September · 10am–9pmReasonably confident

10am–9pm — no rain since Sunday, ground firm

Good:Grass wetness
Grass dryno rain since Sunday
Good:Ground firmness
Ground firm5mm rain over the last week
Good:Growth
Growing steadilygrowth potential 0.43
Good:Temperature
Temperature12°C
Good:Wind
Wind light6 km/h
Sociable hours
Fine by the neighboursstarts when it stops being antisocial

Limiting factor:none

Monday 7 September: Good. 8am–7pm — no rain in over a week, ground firm

Monday 7 September · 8am–7pmReasonably confident

8am–7pm — no rain in over a week, ground firm

Good:Grass wetness
Grass dryno rain in over a week
Good:Ground firmness
Ground firm4mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.69
Good:Temperature
Temperature12°C
Good:Wind
Wind light5 km/h
Sociable hours
A bit early or late, but finestarts when it stops being antisocial

Limiting factor:none

Tuesday 8 September: Marginal. No — 1.0mm of rain falling.

Tuesday 8 SeptemberReasonably confident

No — 1.0mm of rain falling.

Poor:Grass wetness
Grass wetraining now
Good:Ground firmness
Ground firm0mm rain over the last week
Good:Growth
Growing steadilygrowth potential 0.48
Good:Temperature
Temperature12°C
Good:Wind
Wind light5 km/h

Limiting factor:grass wetness

Wednesday 9 September: Not worth it. No — ground frozen.

Wednesday 9 SeptemberLow confidence this far out

No — ground frozen.

Marginal:Grass wetness
Grass dryrain earlier today
Good:Ground firmness
Ground firm16mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.61
Good:Temperature
Temperature11°C
Good:Wind
Wind light7 km/h

Limiting factor:grass wetness

Thursday 10 September: Not worth it. No — ground frozen.

Thursday 10 SeptemberLow confidence this far out

No — ground frozen.

Good:Grass wetness
Grass dryno rain since Tuesday
Good:Ground firmness
Ground firm16mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.99
Good:Temperature
Temperature16°C
Marginal:Wind
Wind light20 km/h

Limiting factor:none

Soil temperature

25.4°C78°F

at 6cm — germination depth

Cooling over the next 11 days.

Seeding conditions are open — soil is 25.4°C at 6cm and holding above 12.5°C.

Most cool-season lawns in the northern US and Canada are bluegrass, tall fescue, or a mix of the two. We assume that, and use12.5°C as the seeding threshold.

I know what grass I have

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 tempDays
Perennial ryegrass8°C5–10
Red / chewings fescue8–10°C10–14
Tall fescuelikely yours10–12°C10–14
Browntop bentColonial bentgrass10–12°C14–21
Smooth-stalked meadow grassKentucky bluegrasslikely yours12–13°C14–28

What this means right now

  • Good: Seeding window open

    Seeding conditions are open — soil is 25.4°C at 6cm and holding above 12.5°C.

  • Warning: Heat stress

    Tuesday 1 September gets hot enough to stress the sward. Mow early or late, and raise the height.

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Forecast from Open-Meteo, refreshed hourly. Soil temperature is modelled, not measured — how that works and where the thresholds come from.