Climate averages 1991–2020
O'Fallon weather
in March.
A cool, wet month: the 8th warmest and the 9th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
March is a cool month in O'Fallon: daytime highs average 12.6°C and nights cool to about 2.6°C. By daytime temperature it is the 8th warmest of the 12 months.
Expect about 92 mm of rain on roughly 11 days, which makes March a wet month (the 9th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 11 h 55 min on an average March day.
The nearest other city in this atlas is St. Louis (48 km away). In March its highs average 13.0°C, about as warm as O'Fallon, with 94 mm of rain.
Among the 498 cities listed in the United States, O'Fallon ranks joint 294th of 498 for the warmest March highs and joint 310th of 498 for the driest March (rainfall, lowest first). The mean March high of those 498 cities is 14.9°C; O'Fallon is 2.3°C cooler than that mean.
From March to April, average highs rise by 6.1°C to 18.7°C, and monthly rainfall rises from 92 mm to 114 mm.
The annual picture
March 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
O'Fallon climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 4.0°C-4.4°C | -4.4°C | 65 | 7.7 | 9.810 h |
| February | 6.8°C-2.6°C | -2.6°C | 61 | 7.7 | 10.711 h |
| March, selected | 12.6°C2.6°C | 2.6°C | 92 | 10.6 | 11.912 h |
| April | 18.7°C8.5°C | 8.5°C | 114 | 11.3 | 13.213 h |
| May | 23.8°C14.3°C | 14.3°C | 123 | 13.3 | 14.314 h |
| June | 28.6°C19.3°C | 19.3°C | 101 | 11.0 | 14.815 h |
| July | 30.8°C21.6°C | 21.6°C | 82 | 9.9 | 14.615 h |
| August | 30.1°C20.9°C | 20.9°C | 76 | 9.1 | 13.714 h |
| September | 26.0°C16.7°C | 16.7°C | 81 | 7.6 | 12.512 h |
| October | 19.5°C10.4°C | 10.4°C | 84 | 8.4 | 11.211 h |
| November | 12.0°C3.7°C | 3.7°C | 89 | 8.3 | 10.110 h |
| December | 6.1°C-1.7°C | -1.7°C | 62 | 7.8 | 9.510 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
March in nearby cities
- St. Louis in MarchUnited States · 48 kmHigh 13.0°C · Low 2.6°C · 94 mm rain
- Columbia (Missouri), United States in MarchUnited States · 142 kmHigh 12.6°C · Low 2.4°C · 86 mm rain
- Springfield (Illinois), United States in MarchUnited States · 143 kmHigh 10.9°C · Low 0.8°C · 80 mm rain
- Decatur in MarchUnited States · 189 kmHigh 10.7°C · Low 0.7°C · 83 mm rain
- Peoria (Illinois), United States in MarchUnited States · 230 kmHigh 9.9°C · Low 0.1°C · 75 mm rain
- Bloomington (Illinois), United States in MarchUnited States · 237 kmHigh 9.8°C · Low -0.3°C · 78 mm rain
- Champaign in MarchUnited States · 256 kmHigh 10.2°C · Low 0.0°C · 85 mm rain
- Springfield (Missouri), United States in MarchUnited States · 289 kmHigh 13.8°C · Low 3.4°C · 101 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 O'Fallon) is explained once on the O'Fallon year overview and on the Sources, method and limits page.