Soil temperature in Chicago, Illinois
Soil temperature
89°F31.6°C
at 6cm — germination depth
Cooling over the next 11 days.
Too warm to seed — the soil is heat-stressed. Wait for it to cool.
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 |
Soil temperature at 6cm in Chicago, Illinois is currently 31.6°C, and falling about 28.6°C over the next 11 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 Kentucky bluegrass with tall fescue, the usual mix for cool-season lawns at this latitude. That blend needs the soil to hold above 12.5°C before seed germinates reliably. Too warm to seed — the soil is heat-stressed. Wait for it to cool.
8 of the next 10 days are good mowing days. The best weekend slot right now is Monday 10am–8pm, on the basis that no rain since Saturday, ground firm.
The next recommended window in Chicago opens at 8am on Wednesday 2 September, because anything earlier is the hour your neighbours will remember. Underfoot, the ground reads as firm after 1mm rain over the last week.
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 31.6°C cooling to 0.0°C
Tuesday 1 September: Good. No — heat stress, 30°C.
Tuesday 1 SeptemberConfident
No — heat stress, 30°C.
- Good:Grass wetness
- Grass dryno rain since Sunday
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Good:Growth
- Growing steadilygrowth potential 0.39
- Poor:Temperature
- Heat stress30°C
- Good:Wind
- Wind light4 km/h
Limiting factor:temperature
Wednesday 2 September: Good. 8am–midday — growing slowly — growth potential 0.28
Wednesday 2 September · 8am–middayConfident
8am–midday — growing slowly — growth potential 0.28
- Good:Grass wetness
- Grass dryno rain since Sunday
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Marginal:Growth
- Growing slowlygrowth potential 0.28
- Poor:Temperature
- Cool24°C
- Good:Wind
- Wind light10 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:growth
Thursday 3 September: Good. 8am–10am — growing slowly — growth potential 0.32
Thursday 3 September · 8am–10amConfident
8am–10am — growing slowly — growth potential 0.32
- Good:Grass wetness
- Grass dryno rain since Sunday
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Marginal:Growth
- Growing slowlygrowth potential 0.32
- Poor:Temperature
- Cool23°C
- Good:Wind
- Wind light11 km/h
- Sociable hours
- A bit early or late, but finestarts when it stops being antisocial
Limiting factor:growth
Friday 4 September: Good. 3pm–8pm — cool — 25°C
Friday 4 September · 3pm–8pmConfident
3pm–8pm — cool — 25°C
- Good:Grass wetness
- Grass drydried off since a shower 5 hours ago
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Good:Growth
- Growing steadilygrowth potential 0.48
- Marginal:Temperature
- Temperature23°C
- Good:Wind
- Wind light10 km/h
- Sociable hours
- Fine by the neighbours
Limiting factor:temperature
Saturday 5 September: Good. 1pm–8pm — grass dry — rain earlier today
Saturday 5 September · 1pm–8pmReasonably confident
1pm–8pm — grass dry — rain earlier today
- Marginal:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm3mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.78
- Good:Temperature
- Temperature22°C
- Good:Wind
- Wind light10 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:grass wetness
Sunday 6 September: Good. 10am–8pm — no rain since Saturday, ground firm
Sunday 6 September · 10am–8pmReasonably confident
10am–8pm — no rain since Saturday, ground firm
- Good:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm10mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.85
- Good:Temperature
- Temperature20°C
- Good:Wind
- Wind light11 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 Saturday, ground firm
Monday 7 September · 10am–8pmReasonably confident
10am–8pm — no rain since Saturday, ground firm
- Good:Grass wetness
- Grass dryno rain since Saturday
- Good:Ground firmness
- Ground firm9mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.84
- Marginal:Temperature
- Temperature20°C
- Good:Wind
- Wind light8 km/h
- Sociable hours
- Fine by the neighboursstarts when it stops being antisocial
Limiting factor:none
Tuesday 8 September: Good. 10am–8pm — grass dry — dried off since a shower 4 hours ago
Tuesday 8 September · 10am–8pmReasonably confident
10am–8pm — grass dry — dried off since a shower 4 hours ago
- Good:Grass wetness
- Grass drydried off since a shower 4 hours ago
- Good:Ground firmness
- Ground firm9mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.83
- Good:Temperature
- Temperature21°C
- Good:Wind
- Wind light4 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
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 drydried off since a shower 5 hours ago
- Good:Ground firmness
- Ground firm10mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.80
- Marginal:Temperature
- Temperature21°C
- Good:Wind
- Wind light13 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 dryrain earlier today
- Good:Ground firmness
- Ground firm13mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.90
- Good:Temperature
- Temperature18°C
- Good:Wind
- Wind light20 km/h
Limiting factor:none
Nearby
Your own postcode
These are town-centre figures. Yours will differ a little.