Missoula, Montana

Best weekend slot

Sunday 11am–7pm

Verdict: Good

rain earlier today, ground firm

Next mow

Tomorrow 8am–2pm

Verdict: Good

rain earlier today, ground firm

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 24.8°C cooling to 0.0°C

Tuesday 1 September: Not worth it. No — 1.4mm of rain falling.

Tuesday 1 SeptemberConfident

No — 1.4mm of rain falling.

Poor:Grass wetness
Grass wetraining now
Good:Ground firmness
Ground firm3mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.99
Good:Temperature
Temperature19°C
Good:Wind
Wind light19 km/h

Limiting factor:grass wetness

Wednesday 2 September: Good. 8am–2pm — rain earlier today, ground firm

Wednesday 2 September · 8am–2pmConfident

8am–2pm — rain earlier today, ground firm

Good:Grass wetness
Grass dryrain earlier today
Good:Ground firmness
Ground firm3mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.93
Good:Temperature
Temperature14°C
Good:Wind
Wind light11 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 — rain earlier today, ground firm

Thursday 3 September · 8am–9pmConfident

8am–9pm — rain earlier today, ground firm

Good:Grass wetness
Grass dryrain earlier today
Good:Ground firmness
Ground firm7mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.72
Good:Temperature
Temperature10°C
Good: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. 4pm–9pm — dried off since a shower 4 hours ago, ground firm

Friday 4 September · 4pm–9pmConfident

4pm–9pm — dried off since a shower 4 hours ago, ground firm

Poor:Grass wetness
Grass drydried off since a shower 4 hours ago
Good:Ground firmness
Ground firm7mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.54
Good:Temperature
Temperature11°C
Good:Wind
Wind light6 km/h
Sociable hours
Fine by the neighboursstarts once the dew has burnt off

Limiting factor:none

Saturday 5 September: Good. 10am–9pm — rain earlier today, ground firm

Saturday 5 September · 10am–9pmReasonably confident

10am–9pm — rain earlier today, ground firm

Good:Grass wetness
Grass dryrain earlier today
Good:Ground firmness
Ground firm16mm rain over the last week
Good:Growth
Growing steadilygrowth potential 0.49
Good:Temperature
Temperature11°C
Good:Wind
Wind light3 km/h
Sociable hours
Fine by the neighboursstarts once the dew has burnt off

Limiting factor:none

Sunday 6 September: Good. 11am–7pm — rain earlier today, ground firm

Sunday 6 September · 11am–7pmReasonably confident

11am–7pm — rain earlier today, ground firm

Good:Grass wetness
Grass dryrain earlier today
Good:Ground firmness
Ground firm16mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.80
Good:Temperature
Temperature11°C
Good:Wind
Wind light3 km/h
Sociable hours
Fine by the neighboursstarts once the dew has burnt off

Limiting factor:none

Monday 7 September: Good. 1pm–9pm — dried off since a shower 1 hour ago, ground firm

Monday 7 September · 1pm–9pmReasonably confident

1pm–9pm — dried off since a shower 1 hour ago, ground firm

Good:Grass wetness
Grass drydried off since a shower 0 hours ago
Good:Ground firmness
Ground firm14mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.85
Good:Temperature
Temperature14°C
Good:Wind
Wind light5 km/h
Sociable hours
Fine by the neighboursstarts once the rain has passed

Limiting factor:none

Tuesday 8 September: Good. 8am–10am — growing slowly — growth potential 0.34

Tuesday 8 September · 8am–10amReasonably confident

8am–10am — growing slowly — growth potential 0.34

Poor:Grass wetness
Grass dryrain earlier today
Good:Ground firmness
Ground firm14mm rain over the last week
Marginal:Growth
Growing slowlygrowth potential 0.34
Good:Temperature
Temperature11°C
Good:Wind
Wind light5 km/h
Sociable hours
A bit early or late, but finestarts at first light

Limiting factor:growth

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 0.56
Good:Temperature
Temperature10°C
Good:Wind
Wind light5 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 firm13mm rain over the last week
Good:Growth
Growing wellgrowth potential 0.85
Good:Temperature
Temperature12°C
Good:Wind
Wind light4 km/h

Limiting factor:none

Soil temperature

77°F24.8°C

at 6cm — germination depth

Cooling over the next 11 days.

Seeding conditions are open — soil is 24.8°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 24.8°C at 6cm and holding above 12.5°C.

  • Warning: Heat stress

    Sunday 6 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.