Climate averages 1991–2020
Wyoming weather
in September.
A warm, moderately wet month: the 4th warmest and the 6th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Wyoming: daytime highs average 22.1°C and nights cool to about 13.5°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 79 mm of rain on roughly 9 days, which makes September a moderately wet month (the 6th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 32 min on an average September day.
The nearest other city in this atlas is Grand Rapids (6 km away). In September its highs average 22.1°C, about as warm as Wyoming, with 79 mm of rain.
Among the 498 cities listed in the United States, Wyoming ranks joint 451st of 498 for the warmest September highs and joint 272nd of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Wyoming is 4.8°C cooler than that mean.
From September to October, average highs fall by 7.1°C to 15.0°C, and monthly rainfall rises from 79 mm to 86 mm.
The annual picture
September in context
Monthly precipitation
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
Wyoming climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -1.1°C-8.1°C | -8.1°C | 62 | 10.5 | 9.49 h |
| February | 0.3°C-8.2°C | -8.2°C | 50 | 8.1 | 10.511 h |
| March | 6.2°C-3.3°C | -3.3°C | 63 | 9.3 | 11.912 h |
| April | 13.2°C3.0°C | 3.0°C | 101 | 12.1 | 13.413 h |
| May | 19.5°C9.6°C | 9.6°C | 108 | 11.9 | 14.615 h |
| June | 24.7°C15.3°C | 15.3°C | 95 | 11.3 | 15.315 h |
| July | 26.7°C17.8°C | 17.8°C | 96 | 10.8 | 15.015 h |
| August | 25.8°C17.3°C | 17.3°C | 92 | 10.5 | 13.914 h |
| September, selected | 22.1°C13.5°C | 13.5°C | 79 | 9.3 | 12.513 h |
| October | 15.0°C7.4°C | 7.4°C | 86 | 11.4 | 11.111 h |
| November | 7.7°C1.3°C | 1.3°C | 68 | 10.0 | 9.810 h |
| December | 1.9°C-3.8°C | -3.8°C | 60 | 10.8 | 9.19 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet 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
September in nearby cities
- Grand Rapids in SeptemberUnited States · 6 kmHigh 22.1°C · Low 13.6°C · 79 mm rain
- Kalamazoo in SeptemberUnited States · 70 kmHigh 22.4°C · Low 13.6°C · 79 mm rain
- Lansing in SeptemberUnited States · 96 kmHigh 22.3°C · Low 13.5°C · 71 mm rain
- South Bend in SeptemberUnited States · 144 kmHigh 23.1°C · Low 13.9°C · 83 mm rain
- Flint in SeptemberUnited States · 165 kmHigh 22.2°C · Low 13.5°C · 72 mm rain
- Racine in SeptemberUnited States · 171 kmHigh 20.8°C · Low 17.0°C · 81 mm rain
- Ann Arbor in SeptemberUnited States · 176 kmHigh 22.3°C · Low 13.3°C · 69 mm rain
- Kenosha in SeptemberUnited States · 177 kmHigh 21.0°C · Low 17.1°C · 80 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 Wyoming) is explained once on the Wyoming year overview and on the Sources, method and limits page.
Grand Rapids lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.