London, Ontario
Best weekend slot
Sunday 10am–8pm
Verdict: Good
no rain since Friday, ground firm
Next mow
Tomorrow 11am–2pm
Verdict: Good
grass dry — rain earlier today
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 23.0°C cooling to 0.0°C
Tuesday 1 September: Not worth it. No — cool, 25°C.
Tuesday 1 SeptemberConfident
No — cool, 25°C.
- Good:Grass wetness
- Grass dryno rain since Monday
- Good:Ground firmness
- Ground firm23mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.69
- Marginal:Temperature
- Cool24°C
- Good:Wind
- Wind light6 km/h
Limiting factor:temperature
Wednesday 2 September: Good. 11am–2pm — grass dry — rain earlier today
Wednesday 2 September · 11am–2pmConfident
11am–2pm — grass dry — rain earlier today
- Good:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm23mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.64
- Marginal:Temperature
- Temperature22°C
- Good:Wind
- Wind light9 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:grass wetness
Thursday 3 September: Good. 8am–11am — no rain since Wednesday, ground firm
Thursday 3 September · 8am–11amConfident
8am–11am — no rain since Wednesday, ground firm
- Good:Grass wetness
- Grass dryno rain since Wednesday
- Good:Ground firmness
- Ground firm24mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.84
- Marginal:Temperature
- Temperature19°C
- Good:Wind
- Wind light9 km/h
- Sociable hours
- A bit early or late, but finestarts once the dew has burnt off
Limiting factor:none
Friday 4 September: Good. 4pm–8pm — grass dry — rain earlier today
Friday 4 September · 4pm–8pmConfident
4pm–8pm — grass dry — rain earlier today
- Poor:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm26mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 1.00
- Good:Temperature
- Temperature16°C
- Good:Wind
- Wind light8 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:grass wetness
Saturday 5 September: Good. 8am–8pm — rain earlier today, ground firm
Saturday 5 September · 8am–8pmReasonably confident
8am–8pm — rain earlier today, ground firm
- Good:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm34mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.91
- Good:Temperature
- Temperature13°C
- Good:Wind
- Wind light10 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:none
Sunday 6 September: Good. 10am–8pm — no rain since Friday, ground firm
Sunday 6 September · 10am–8pmReasonably confident
10am–8pm — no rain since Friday, ground firm
- Good:Grass wetness
- Grass dryno rain since Friday
- Good:Ground firmness
- Ground firm34mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.85
- Good:Temperature
- Temperature12°C
- Good:Wind
- Wind light10 km/h
- Sociable hours
- Fine by the neighboursstarts when it stops being antisocial
Limiting factor:none
Monday 7 September: Good. 8am–8pm — no rain since Friday, ground firm
Monday 7 September · 8am–8pmReasonably confident
8am–8pm — no rain since Friday, ground firm
- Good:Grass wetness
- Grass dryno rain since Friday
- Good:Ground firmness
- Ground firm16mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.92
- Good:Temperature
- Temperature14°C
- Good:Wind
- Wind light8 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:none
Tuesday 8 September: Good. 8am–8pm — no rain since Friday, ground firm
Tuesday 8 September · 8am–8pmReasonably confident
8am–8pm — no rain since Friday, ground firm
- Good:Grass wetness
- Grass dryno rain since Friday
- Good:Ground firmness
- Ground firm12mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.97
- Good:Temperature
- Temperature16°C
- Good:Wind
- Wind light8 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:none
Wednesday 9 September: Not worth it. No — ground frozen.
Wednesday 9 SeptemberLow confidence this far out
No — ground frozen.
- Good:Grass wetness
- Grass dryno rain since Friday
- Good:Ground firmness
- Ground firm12mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.88
- Good:Temperature
- Temperature13°C
- Good:Wind
- Wind light16 km/h
Limiting factor:none
Thursday 10 September: Not worth it. No — ground frozen.
Thursday 10 SeptemberLow confidence this far out
No — ground frozen.
- Marginal:Grass wetness
- Grass drydried off since a shower 0 hours ago
- Good:Ground firmness
- Ground firm11mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.96
- Good:Temperature
- Temperature20°C
- Good:Wind
- Wind light19 km/h
Limiting factor:grass wetness
Soil temperature
23.2°C74°F
at 6cm — germination depth
Cooling over the next 11 days.
Seeding conditions are open — soil is 23.2°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.
| Species | Soil temp | Days |
|---|---|---|
| Perennial ryegrass | 8°C | 5–10 |
| Red / chewings fescue | 8–10°C | 10–14 |
| Tall fescuelikely yours | 10–12°C | 10–14 |
| Browntop bentColonial bentgrass | 10–12°C | 14–21 |
| Smooth-stalked meadow grassKentucky bluegrasslikely yours | 12–13°C | 14–28 |
What this means right now
Good: Seeding window open
Seeding conditions are open — soil is 23.2°C at 6cm and holding above 12.5°C.
Warning: Heat stress
Wednesday 2 September gets hot enough to stress the sward. Mow early or late, and raise the height.
Forecast from Open-Meteo, refreshed hourly. Soil temperature is modelled, not measured — how that works and where the thresholds come from.