Sioux Falls weather by month
Sioux Falls runs from about -9°C in January to 23°C in July, with June the wettest month at 194 mm.
warmest month
July
23°C
coolest month
January
-9°C
wettest month
June
194 mm
worst air month
March
8 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | -9°C | 33 mm | 165 h | 6 |
| February | 1°C | 7 mm | 240 h | 7 |
| March | 2°C | 38 mm | 271 h | 8 |
| April | 9°C | 157 mm | 290 h | 6 |
| May | 16°C | 176 mm | 356 h | 6 |
| June | 21°C | 194 mm | 351 h | 6 |
| July | 23°C | 38 mm | 408 h | 7 |
| August | 22°C | 28 mm | 354 h | 7 |
| September | 20°C | 9 mm | 354 h | 7 |
| October | 14°C | 19 mm | 301 h | 4 |
| November | 3°C | 40 mm | 193 h | 5 |
| December | -3°C | 21 mm | 140 h | 8 |
About 3,423 hours of sun a year. Roughly 77 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-24. Full method, licences and the list of sources we rejected are on the methodology page.