Marietta, IL
Climate overview — based on NOAA 1991-2020 normals from PRAIRIE CITY 2S, IL US.
Year-round temperatures (°F)
Climate summary
Marietta has an annual average temperature of 51.5°F with about 38.5 inches of precipitation per year and 21.3 inches of snow. The warmest month is July (average high 85.7°F), and the coldest is January (average low 16.0°F). May is typically the wettest month (5.05 in) and December the driest (1.80 in). Snow typically falls from November through April.
Best time to visit Marietta
Full guide →Climate change signal
All-time records →132 of 366 (36.1%) of Marietta'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.
| 2000s | 124 | |
| 2010s | 180 | |
| 2020s | 62 |
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 | 32.7°F | 16.0°F | 24.4°F | 1.91 in | 5.7 in | 7 |
| February | 37.9°F | 19.0°F | 28.5°F | 1.92 in | 6.0 in | 8 |
| March | 50.5°F | 28.8°F | 39.6°F | 2.68 in | 2.5 in | 9 |
| April | 63.6°F | 39.8°F | 51.7°F | 3.79 in | 1.0 in | 11 |
| May | 73.8°F | 52.0°F | 62.9°F | 5.05 in | — | 12 |
| June | 82.4°F | 61.6°F | 72.0°F | 4.82 in | — | 10 |
| July | 85.7°F | 64.4°F | 75.1°F | 4.10 in | — | 9 |
| August | 83.5°F | 62.5°F | 73.0°F | 3.21 in | — | 8 |
| September | 78.0°F | 54.9°F | 66.4°F | 3.77 in | — | 7 |
| October | 66.0°F | 43.0°F | 54.5°F | 2.99 in | — | 9 |
| November | 50.2°F | 30.8°F | 40.5°F | 2.42 in | 1.1 in | 8 |
| December | 38.1°F | 21.7°F | 29.9°F | 1.80 in | 5.0 in | 8 |
Climate twins of Marietta
Why these? →The most climatically similar US cities at least 140 miles away (by monthly temperature + precipitation pattern).