Soil temperature in Bethlehem, Pennsylvania
Soil temperature
78°F25.3°C
at 6cm — germination depth
Cooling over the next 11 days.
Seeding conditions are open — soil is 25.3°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 |
Soil temperature at 6cm in Bethlehem, Pennsylvania is currently 25.3°C, and falling about 23.0°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. Seeding conditions are open — soil is 25.3°C at 6cm and holding above 12.5°C.
7 of the next 10 days are good mowing days. The other 3 are held back by wet grass or soft ground. The best weekend slot right now is Saturday 10am–8pm, on the basis that rain earlier today, ground firm.
The next recommended window in Bethlehem opens at 10am on Thursday 3 September, because that is when the dew has burnt off — earlier than that and you are cutting wet grass. Underfoot, the ground reads as firm after 18mm 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 24.2°C cooling to 0.0°C
Tuesday 1 September: Not worth it. No — 7.2mm of rain falling.
Tuesday 1 SeptemberConfident
No — 7.2mm of rain falling.
- Poor:Grass wetness
- Grass wetraining now
- Good:Ground firmness
- Ground firm18mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.77
- Good:Temperature
- Temperature23°C
- Good:Wind
- Wind light10 km/h
Limiting factor:grass wetness
Wednesday 2 September: Good. No — grass wet, rain earlier today.
Wednesday 2 SeptemberConfident
No — grass wet, rain earlier today.
- Poor:Grass wetness
- Grass wetrain earlier today
- Good:Ground firmness
- Ground firm18mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.95
- Good:Temperature
- Temperature20°C
- Good:Wind
- Wind light7 km/h
Limiting factor:grass wetness
Thursday 3 September: Good. 10am–2pm — grass dry — no rain since Tuesday
Thursday 3 September · 10am–2pmConfident
10am–2pm — grass dry — no rain since Tuesday
- Good:Grass wetness
- Grass dryno rain since Tuesday
- Good:Ground firmness
- Ground firm25mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.76
- Marginal:Temperature
- Temperature21°C
- Good:Wind
- Wind light3 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:grass wetness
Friday 4 September: Good. 11am–midday — heat stress — 28°C
Friday 4 September · 11am–middayConfident
11am–midday — heat stress — 28°C
- Marginal:Grass wetness
- Grass drydried off since a shower 4 hours ago
- Good:Ground firmness
- Ground firm28mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.67
- Marginal:Temperature
- Temperature22°C
- Good:Wind
- Wind light4 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
Limiting factor:temperature
Saturday 5 September: Good. 10am–8pm — rain earlier today, ground firm
Saturday 5 September · 10am–8pmReasonably confident
10am–8pm — rain earlier today, ground firm
- Good:Grass wetness
- Grass dryrain earlier today
- Good:Ground firmness
- Ground firm14mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.99
- Good:Temperature
- Temperature15°C
- Good:Wind
- Wind light13 km/h
- Sociable hours
- Fine by the neighboursstarts once the dew has burnt off
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 firm17mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.91
- Good:Temperature
- Temperature13°C
- Good:Wind
- Wind light5 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 Friday, ground firm
Monday 7 September · 10am–8pmReasonably confident
10am–8pm — no rain since Friday, ground firm
- Good:Grass wetness
- Grass dryno rain since Friday
- Good:Ground firmness
- Ground firm17mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.94
- Good:Temperature
- Temperature14°C
- Good:Wind
- Wind light3 km/h
- Sociable hours
- Fine by the neighboursstarts when it stops being antisocial
Limiting factor:none
Tuesday 8 September: Good. 8am–midday — no rain since Friday, ground firm
Tuesday 8 September · 8am–middayReasonably confident
8am–midday — 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 0.97
- Good:Temperature
- Temperature16°C
- Good:Wind
- Wind light4 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 dryrain earlier today
- Good:Ground firmness
- Ground firm16mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.97
- Good:Temperature
- Temperature16°C
- Good:Wind
- Wind light9 km/h
Limiting factor:none
Thursday 10 September: Not worth it. No — ground frozen.
Thursday 10 SeptemberLow confidence this far out
No — ground frozen.
- Poor:Grass wetness
- Grass drydried off since a shower 0 hours ago
- Good:Ground firmness
- Ground firm10mm rain over the last week
- Good:Growth
- Growing wellgrowth potential 0.89
- Good:Temperature
- Temperature21°C
- Good:Wind
- Wind light8 km/h
Limiting factor:grass wetness
Nearby
Your own postcode
These are town-centre figures. Yours will differ a little.