Seneca, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Seneca, a village in Lasalle County, Illinois.
Tonight
66°F
Mostly Cloudy then Chance Showers And Thunderstorms
A chance of showers and thunderstorms after 2am. Mostly cloudy, with a low around 66. East southeast wind around 10 mph, with gusts as high as 20 mph. Chance of precipitation is 30%. New rainfall amounts between a quarter and half of an inch possible.
7-day forecast for Seneca
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 66°F | Mostly Cloudy then Chance Showers And Thunderstorms | 10 mph ESE | 27% |
| Saturday | 83°F | Showers And Thunderstorms Likely | 5 to 10 mph SE | 65% |
| Saturday Night | 67°F | Showers And Thunderstorms Likely | 5 mph W | 79% |
| Sunday | 72°F | Showers And Thunderstorms | 5 to 15 mph NNE | 79% |
| Sunday Night | 58°F | Showers And Thunderstorms Likely | 10 to 15 mph NE | 71% |
| Monday | 66°F | Showers And Thunderstorms Likely | 15 mph ENE | 62% |
| Monday Night | 54°F | Chance Rain Showers | 10 to 15 mph NE | 33% |
| Tuesday | 64°F | Slight Chance Rain Showers | 10 mph NE | 24% |
| Tuesday Night | 54°F | Mostly Cloudy | 5 to 10 mph NNE | 10% |
| Wednesday | 68°F | Partly Sunny | 5 to 10 mph NNE | 6% |
| Wednesday Night | 54°F | Partly Cloudy | 0 to 10 mph NNE | 5% |
| Thursday | 70°F | Mostly Sunny | 0 to 5 mph N | 2% |
| Thursday Night | 55°F | Partly Cloudy | 0 to 5 mph NNE | 3% |
| Friday | 72°F | Mostly Sunny | 0 to 5 mph NNE | 4% |
Forecast source: National Weather Service (api.weather.gov) for Seneca (41.303, -88.615). Updated through the day.
Growing snapshot for Seneca
Last spring frost
Apr 27
First fall frost
Oct 17
Growing season
171 days
Hardiness zone
5b
More local growing data for Seneca: nearby ZIP 61360 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Cedar Point
Dana
Dayton
Earlville
Grand Ridge
Harding
Kangley
LaSalle
Leland
Leonore
Lostant
Marseilles
Mendota
Millington
Naplate
Newark
North Utica
Oglesby
Ottawa
Peru
Ransom
Rutland
Serena
Sheridan
Streator
Tonica
Triumph
Troy Grove
Wedron
Wenona
Climate data from the nearest NOAA station, Marseilles Lock, Il (7.9 mi from Seneca). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.