Ottawa, IL
Climate overview — based on NOAA 1991-2020 normals from MARSEILLES LOCK, IL US.
Year-round temperatures (°F)
Climate summary
Ottawa has an annual average temperature of 49.7°F with about 39 inches of precipitation per year and 25 inches of snow. The warmest month is July (average high 84.0°F), and the coldest is January (average low 14.2°F). June is typically the wettest month (4.92 in) and February the driest (1.90 in). Snow typically falls from November through April.
Best time to visit Ottawa
Full guide →Climate change signal
All-time records →135 of 366 (36.9%) of Ottawa's all-time daily heat records have been set since 2015. If records were spread evenly across the station's history, only about 5% would fall in any given decade.
| 1940s | 2 | |
| 1950s | 0 | |
| 1960s | 0 | |
| 1970s | 15 | |
| 1980s | 0 | |
| 1990s | 31 | |
| 2000s | 113 | |
| 2010s | 121 | |
| 2020s | 84 |
Bars: number of all-time daily heat records still standing that were set in each decade.
Monthly averages
| Month | Avg High | Avg Low | Avg Temp | Precipitation | Snow | Rainy days |
|---|---|---|---|---|---|---|
| January | 31.4°F | 14.2°F | 22.8°F | 1.95 in | 8.4 in | 11 |
| February | 35.4°F | 17.2°F | 26.3°F | 1.90 in | 7.3 in | 10 |
| March | 47.5°F | 27.2°F | 37.3°F | 2.54 in | 2.9 in | 11 |
| April | 61.2°F | 37.3°F | 49.2°F | 3.59 in | 0.3 in | 12 |
| May | 72.6°F | 48.5°F | 60.5°F | 4.70 in | — | 12 |
| June | 81.1°F | 58.1°F | 69.6°F | 4.92 in | — | 11 |
| July | 84.0°F | 61.9°F | 73.0°F | 3.85 in | — | 9 |
| August | 82.4°F | 60.5°F | 71.5°F | 4.09 in | — | 9 |
| September | 77.1°F | 52.9°F | 65.0°F | 3.46 in | — | 8 |
| October | 64.1°F | 41.2°F | 52.7°F | 3.20 in | — | 10 |
| November | 49.1°F | 30.0°F | 39.6°F | 2.72 in | 0.8 in | 10 |
| December | 36.6°F | 20.5°F | 28.5°F | 2.11 in | 5.3 in | 11 |
Climate twins of Ottawa
Why these? →The most climatically similar US cities at least 140 miles away (by monthly temperature + precipitation pattern).