Seneca, IL Weather & Growing Conditions
Overnight
60°F
Slight Chance Rain Showers
A slight chance of rain showers. Cloudy. Low around 60, with temperatures rising to around 62 overnight. South southwest wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 20%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 60°F | Slight Chance Rain Showers | 15 mph SSW | 23% |
| Wednesday | 63°F | Patchy Drizzle | 15 mph SW | 18% |
| Wednesday Night | 47°F | Patchy Drizzle then Mostly Cloudy | 15 mph SW | 10% |
| Thursday | 58°F | Mostly Cloudy then Chance Rain Showers | 10 to 15 mph WSW | 31% |
| Thursday Night | 42°F | Chance Rain Showers | 10 mph NW | 44% |
| Friday | 52°F | Partly Sunny | 10 to 15 mph NNW | 10% |
| Friday Night | 33°F | Partly Cloudy | 5 to 10 mph NNW | 0% |
| Saturday | 53°F | Sunny | 5 mph NW | 0% |
| Saturday Night | 34°F | Mostly Clear | 0 mph | 1% |
| Sunday | 56°F | Sunny | 0 to 10 mph W | 4% |
| Sunday Night | 34°F | Clear | 0 to 5 mph W | 0% |
| Monday | 63°F | Sunny | 0 to 5 mph SW | 0% |
| Monday Night | 39°F | Mostly Clear | 0 to 5 mph WSW | 1% |
| Tuesday | 63°F | Sunny | 0 to 5 mph WNW | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Seneca, IL
Last spring frost
Apr 27
First fall frost
Oct 17
Growing season
171 days
Hardiness zone
5b
Explore more for Seneca, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Marseilles Lock, Il (7.9 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.