Ottawa Weather Forecast
- 11
- 50
Rain Showers
- 23
- 28
Partly Sunny
- 19
- 43
Mostly Cloudy
- 23
- 33
Partly Sunny
- 34
- 40
Mostly Cloudy
- 29
- 47
Mostly Cloudy
Today 18 Dec La Salle
Rain Showers with patchy drizzle in the Morning, then a chance of rain Showers in the afternoon. A slight chance of freezing drizzle late. Ice accumulation around a trace. Windy with Highs in the upper 40s. Temperature falling into the mid 30s in the afternoon. South Winds 15 to 20 Mph, becoming west 15 to 25 Mph in the afternoon. Gusts up to 40 Mph. Chance of precipitation near 100 percent.
Tonight 18 Dec La Salle
Mostly cloudy. Scattered snow Showers in the Evening, then a chance of Flurries after midnight. Little or no snow accumulation. Windy with Lows around 11. West Winds 15 to 25 Mph with Gusts up to 40 Mph. Chance of precipitation 40 percent. Wind chill Values as low as 9 below.
Ottawa Temperature Statistics
December Temperature
Illinois Valley Regional Airport (15.5 miles)
Lowest 14 December, 2025
-3.3 °FAverage December
20.5 °FHighest 10 December, 2025
44.2 °F
Climate (2020–Present)
Illinois Valley Regional Airport (15.5 miles)
Average Low 2020–2025
43.1 °FAverage 2020–2025
52.6 °FAverage High 2020–2025
62.1 °F