Climate averages 1991–2020
Longmont weather
in August.
A hot, fairly dry month: the 2nd warmest and the joint 5th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
August is a hot month in Longmont: daytime highs average 28.3°C and nights cool to about 14.3°C. By daytime temperature it is the 2nd warmest of the 12 months.
Expect about 39 mm of rain on roughly 7 days, which makes August a fairly dry month (the joint 5th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 46 min on an average August day.
The nearest other city in this atlas is Boulder (22 km away). In August its highs average 27.5°C, 0.8°C cooler than Longmont, with 71 mm of rain.
Among the 498 cities listed in the United States, Longmont ranks joint 310th of 498 for the warmest August highs and joint 168th of 498 for the driest August (rainfall, lowest first). The mean August high of those 498 cities is 29.9°C; Longmont is 1.6°C cooler than that mean.
From August to September, average highs fall by 4.2°C to 24.2°C, and monthly rainfall stays at 39 mm.
The annual picture
August in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Longmont climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 4.5°C-8.4°C | -8.4°C | 19 | 4.7 | 9.710 h |
| February | 5.9°C-7.6°C | -7.6°C | 20 | 5.3 | 10.611 h |
| March | 11.0°C-3.9°C | -3.9°C | 42 | 7.3 | 11.912 h |
| April | 14.8°C0.4°C | 0.4°C | 67 | 9.5 | 13.213 h |
| May | 19.9°C5.9°C | 5.9°C | 87 | 11.7 | 14.414 h |
| June | 26.0°C11.4°C | 11.4°C | 53 | 8.4 | 15.015 h |
| July | 29.5°C15.0°C | 15.0°C | 42 | 7.3 | 14.715 h |
| August, selected | 28.3°C14.3°C | 14.3°C | 39 | 6.7 | 13.814 h |
| September | 24.2°C9.9°C | 9.9°C | 39 | 5.9 | 12.512 h |
| October | 16.8°C3.2°C | 3.2°C | 41 | 6.5 | 11.211 h |
| November | 9.4°C-3.6°C | -3.6°C | 28 | 5.8 | 10.010 h |
| December | 4.2°C-8.1°C | -8.1°C | 18 | 4.5 | 9.49 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
August in nearby cities
- Boulder in AugustUnited States · 22 kmHigh 27.5°C · Low 13.7°C · 71 mm rain
- Loveland in AugustUnited States · 26 kmHigh 28.2°C · Low 14.0°C · 37 mm rain
- Thornton in AugustUnited States · 35 kmHigh 28.0°C · Low 13.8°C · 39 mm rain
- Westminster (Colorado), United States in AugustUnited States · 37 kmHigh 28.1°C · Low 13.8°C · 39 mm rain
- Arvada in AugustUnited States · 41 kmHigh 28.0°C · Low 13.7°C · 39 mm rain
- Greeley in AugustUnited States · 44 kmHigh 30.5°C · Low 16.0°C · 31 mm rain
- Fort Collins in AugustUnited States · 47 kmHigh 28.2°C · Low 14.0°C · 37 mm rain
- Denver in AugustUnited States · 49 kmHigh 28.2°C · Low 13.9°C · 39 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Longmont) is explained once on the Longmont year overview and on the Sources, method and limits page.