Seattle, Washington
Best weekend slot
Saturday 8am–8pm
Verdict: Good
no rain since Thursday, ground firm
Next mow
Today 6pm–8pm
Verdict: Good
no rain since Saturday, ground firm
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 19.4°C cooling to 0.0°C
Tuesday 1 September: Good. 6pm–8pm — no rain since Saturday, ground firm
Tuesday 1 September · 6pm–8pmConfident
6pm–8pm — no rain since Saturday, ground firm
- Good:Grass wetness
- Grass dryno rain since Saturday
- Good:Ground firmness
- Ground firm4mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.82
- Good:Temperature
- Temperature18°C
- Good:Wind
- Wind light9 km/h
- Sociable hours
- A bit early or late, but fine
Limiting factor:none
Wednesday 2 September: Good. 2pm–5pm — dried off since a shower 1 hour ago, ground firm
Wednesday 2 September · 2pm–5pmConfident
2pm–5pm — dried off since a shower 1 hour ago, ground firm
- Good:Grass wetness
- Grass dryno rain since Saturday
- Good:Ground firmness
- Ground firm4mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.74
- Good:Temperature
- Temperature13°C
- Good:Wind
- Wind light9 km/h
- Sociable hours
- Fine by the neighboursstarts once the rain has passed
Limiting factor:none
Thursday 3 September: Good. midday–5pm — rain earlier today, ground firm
Thursday 3 September · midday–5pmConfident
midday–5pm — rain earlier today, ground firm
- Marginal:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm4mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.51
- Good:Temperature
- Temperature11°C
- Good:Wind
- Wind light14 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:none
Friday 4 September: Good. 11am–8pm — rain earlier today, ground firm
Friday 4 September · 11am–8pmConfident
11am–8pm — rain earlier today, ground firm
- Good:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm8mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.62
- Good:Temperature
- Temperature10°C
- Good:Wind
- Wind light3 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:none
Saturday 5 September: Good. 8am–8pm — no rain since Thursday, ground firm
Saturday 5 September · 8am–8pmReasonably confident
8am–8pm — no rain since Thursday, ground firm
- Good:Grass wetness
- Grass dryno rain since Thursday
- Good:Ground firmness
- Ground firm9mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.73
- Good:Temperature
- Temperature10°C
- Good:Wind
- Wind light5 km/h
- Sociable hours
- A bit early or late, but finestarts once the dew has burnt off
Limiting factor:none
Sunday 6 September: Good. 10am–8pm — no rain since Thursday, ground firm
Sunday 6 September · 10am–8pmReasonably confident
10am–8pm — no rain since Thursday, ground firm
- Good:Grass wetness
- Grass dryno rain since Thursday
- Good:Ground firmness
- Ground firm6mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.89
- Good:Temperature
- Temperature12°C
- Good:Wind
- Wind light1 km/h
- Sociable hours
- Fine by the neighboursstarts when it stops being antisocial
Limiting factor:none
Monday 7 September: Good. 10am–8pm — no rain since Thursday, ground firm
Monday 7 September · 10am–8pmReasonably confident
10am–8pm — no rain since Thursday, ground firm
- Good:Grass wetness
- Grass dryno rain since Thursday
- Good:Ground firmness
- Ground firm6mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.98
- Good:Temperature
- Temperature14°C
- Good:Wind
- Wind light1 km/h
- Sociable hours
- Fine by the neighboursstarts when it stops being antisocial
Limiting factor:none
Tuesday 8 September: Good. 8am–6pm — no rain since Thursday, ground firm
Tuesday 8 September · 8am–6pmReasonably confident
8am–6pm — no rain since Thursday, ground firm
- Good:Grass wetness
- Grass dryno rain since Thursday
- Good:Ground firmness
- Ground firm6mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.91
- Good:Temperature
- Temperature15°C
- Good:Wind
- Wind light10 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 Thursday
- Good:Ground firmness
- Ground firm6mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.72
- Good:Temperature
- Temperature12°C
- Good:Wind
- Wind light6 km/h
Limiting factor:none
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 Thursday
- Good:Ground firmness
- Ground firm5mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.94
- Marginal:Temperature
- Temperature13°C
- Good:Wind
- Wind light2 km/h
Limiting factor:none
Soil temperature
67°F19.7°C
at 6cm — germination depth
Cooling over the next 11 days.
Seeding conditions are open — soil is 19.7°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 19.7°C at 6cm and holding above 12.5°C.
Warning: Heat stress
Monday 7 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.