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Seneca, IL Climate
1991 to 2020 normals at Marseilles Lock, 7.5 mi from the center of Seneca, elevation 490 ft.
Average weather by month
Select a month for daily normals and last year's weather
| Month | Range | High | Low | Precip. | Snow |
|---|---|---|---|---|---|
| January | 31° | 14° | 1.95 in | 8.4 in | |
| February | 35° | 17° | 1.90 in | 7.3 in | |
| March | 48° | 27° | 2.54 in | 2.9 in | |
| April | 61° | 37° | 3.59 in | 0.3 in | |
| May | 73° | 49° | 4.70 in | 0.0 in | |
| June | 81° | 58° | 4.92 in | 0.0 in | |
| July | 84° | 62° | 3.85 in | 0.0 in | |
| August | 82° | 61° | 4.09 in | 0.0 in | |
| September | 77° | 53° | 3.46 in | 0.0 in | |
| October | 64° | 41° | 3.20 in | 0.0 in | |
| November | 49° | 30° | 2.72 in | 0.8 in | |
| December | 37° | 21° | 2.11 in | 5.3 in | |
| Year | 60° | 39.03 in | 25.0 in |
Frequently asked questions
- What is the hottest month in Seneca, IL?
- July is the warmest month, with a normal high of 84°F at Marseilles Lock.
- What is the coldest month in Seneca, IL?
- January is the coldest month, with a normal low of 14°F.
- What is the wettest month in Seneca, IL?
- June has the most precipitation on average, about 4.92 inches.