Soil temperature in St Louis, Missouri
Soil temperature
89°F31.4°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 St Louis, Missouri is currently 31.4°C, and falling about 28.9°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.
7 of the next 10 days are good mowing days. The best weekend slot right now is Sunday 10am–11am, on the basis that growing slowly — growth potential 0.30.
The next recommended window in St Louis opens at 10am on Sunday 6 September, because anything earlier is the hour your neighbours will remember. Underfoot, the ground reads as firm after 0mm 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 29.7°C cooling to 0.0°C
Tuesday 1 September: Not worth it. No — barely growing, growth potential 0.20.
Tuesday 1 SeptemberConfident
No — barely growing, growth potential 0.20.
- Good:Grass wetness
- Grass dryno rain in the record
- Good:Ground firmness
- Ground firm0mm rain over the last week
- Poor:Growth
- Barely growinggrowth potential 0.20
- Poor:Temperature
- Heat stress29°C
- Good:Wind
- Wind light10 km/h
Limiting factor:growth
Wednesday 2 September: Good. No — barely growing, growth potential 0.10.
Wednesday 2 SeptemberConfident
No — barely growing, growth potential 0.10.
- Good:Grass wetness
- Grass dryno rain in the record
- Good:Ground firmness
- Ground firm0mm rain over the last week
- Poor:Growth
- Barely growinggrowth potential 0.10
- Poor:Temperature
- Heat stress27°C
- Good:Wind
- Wind light12 km/h
Limiting factor:growth
Thursday 3 September: Good. No — barely growing, growth potential 0.08.
Thursday 3 SeptemberConfident
No — barely growing, growth potential 0.08.
- Good:Grass wetness
- Grass dryno rain in the record
- Good:Ground firmness
- Ground firm0mm rain over the last week
- Poor:Growth
- Barely growinggrowth potential 0.08
- Poor:Temperature
- Heat stress26°C
- Good:Wind
- Wind light8 km/h
Limiting factor:growth
Friday 4 September: Good. No — barely growing, growth potential 0.05.
Friday 4 SeptemberConfident
No — barely growing, growth potential 0.05.
- Good:Grass wetness
- Grass dryno rain in the record
- Good:Ground firmness
- Ground firm0mm rain over the last week
- Poor:Growth
- Barely growinggrowth potential 0.05
- Poor:Temperature
- Heat stress28°C
- Good:Wind
- Wind light8 km/h
Limiting factor:growth
Saturday 5 September: Good. No — 0.2mm of rain falling.
Saturday 5 SeptemberReasonably confident
No — 0.2mm of rain falling.
- Good:Grass wetness
- Grass dryno rain in the record
- Good:Ground firmness
- Ground firm0mm rain over the last week
- Poor:Growth
- Barely growinggrowth potential 0.04
- Poor:Temperature
- Heat stress27°C
- Good:Wind
- Wind light7 km/h
Limiting factor:growth
Sunday 6 September: Good. 10am–11am — growing slowly — growth potential 0.30
Sunday 6 September · 10am–11amReasonably confident
10am–11am — growing slowly — growth potential 0.30
- Good:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm0mm rain over the last week
- Marginal:Growth
- Growing slowlygrowth potential 0.30
- Poor:Temperature
- Temperature23°C
- Good:Wind
- Wind light7 km/h
- Sociable hours
- Fine by the neighboursstarts when it stops being antisocial
Limiting factor:growth
Monday 7 September: Good. No — 0.2mm of rain falling.
Monday 7 SeptemberReasonably confident
No — 0.2mm of rain falling.
- Good:Grass wetness
- Grass drydried off since a shower 1 hour ago
- Good:Ground firmness
- Ground firm1mm rain over the last week
- Marginal:Growth
- Growing slowlygrowth potential 0.29
- Poor:Temperature
- Temperature23°C
- Good:Wind
- Wind light6 km/h
Limiting factor:growth
Tuesday 8 September: Good. No — 0.7mm of rain falling.
Tuesday 8 SeptemberReasonably confident
No — 0.7mm of rain falling.
- Poor:Grass wetness
- Grass drydried off since a shower 2 hours ago
- Good:Ground firmness
- Ground firm3mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.67
- Marginal:Temperature
- Temperature23°C
- Good:Wind
- Wind light13 km/h
Limiting factor:temperature
Wednesday 9 September: Not worth it. No — ground frozen.
Wednesday 9 SeptemberLow confidence this far out
No — ground frozen.
- Good:Grass wetness
- Grass drydried off since a shower 3 hours ago
- Good:Ground firmness
- Ground firm18mm rain over the last week
- Marginal:Growth
- Growing slowlygrowth potential 0.24
- Poor:Temperature
- Cool23°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 drydried off since a shower 0 hours ago
- Good:Ground firmness
- Ground firm21mm rain over the last week
- Good:Growth
- Growing steadilygrowth potential 0.40
- Marginal:Temperature
- Cool23°C
- Good:Wind
- Wind light13 km/h
Limiting factor:none
Nearby
Your own postcode
These are town-centre figures. Yours will differ a little.