Ottawa, IL Weather & Growing Conditions
Overnight
58°F
Chance Rain Showers
A chance of rain showers. Cloudy. Low around 58, with temperatures rising to around 60 overnight. South southwest wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 40%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 58°F | Chance Rain Showers | 15 mph SSW | 38% |
| Wednesday | 62°F | Slight Chance Rain Showers then Mostly Cloudy | 15 mph SW | 17% |
| Wednesday Night | 47°F | Mostly Cloudy | 10 to 15 mph SW | 11% |
| Thursday | 57°F | Mostly Cloudy then Chance Rain Showers | 10 to 15 mph WSW | 32% |
| Thursday Night | 42°F | Chance Rain Showers | 10 mph NW | 42% |
| Friday | 51°F | Partly Sunny | 10 mph NNW | 8% |
| Friday Night | 33°F | Partly Cloudy | 5 to 10 mph NNW | 0% |
| Saturday | 52°F | Sunny | 0 to 5 mph NW | 0% |
| Saturday Night | 34°F | Mostly Clear | 0 to 5 mph W | 1% |
| Sunday | 57°F | Sunny | 5 to 10 mph W | 4% |
| Sunday Night | 34°F | Clear | 0 to 5 mph W | 0% |
| Monday | 62°F | Sunny | 0 to 10 mph SW | 0% |
| Monday Night | 39°F | Mostly Clear | 5 mph WSW | 1% |
| Tuesday | 62°F | Sunny | 5 mph WNW | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Ottawa, IL
Last spring frost
Apr 20
First fall frost
Oct 22
Growing season
183 days
Hardiness zone
5b
Explore more for Ottawa, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Ottawa 5Sw, Il (3.8 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.