Ottawa (IL) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Ottawa.
Climate overview of Ottawa
Temperatures in Ottawa, Illinois, United States of America, vary greatly throughout the year. July is the hottest month at 29°C (84°F), while January is the coldest at -1°C (30°F).
Rain/snowfall is high, totalling around 1008 mm (40 in) per year. June is the wettest month and January the driest.
Ottawa Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Ottawa — and find the best time to visit.
Monthly Temperature in Ottawa
The climate in Ottawa is known for significant temperature differences throughout the year, making the weather dynamic. Average maximum daytime temperatures range from a comfortable 29°C (84°F) in July, the warmest time of the year, to a very cold -1°C (30°F) during cooler months like January.
At night, you can expect temperatures ranging from 18°C (64°F) in July to around -10°C (14°F) during January.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Ottawa
Ottawa has a notably wet climate with abundant precipitation, recording 1008 mm (40 in) of rain/snowfall per year. Significant seasonal changes in precipitation occur throughout the year. In the wettest month, June it receives high rainfall, averaging 129 mm (5.1 in) of precipitation, recorded across 13 rainy days. In contrast, the driest month January brings less snowfall, with 46 mm (1.8 in) over 10 snowy days. For more details, please visit our Ottawa Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Best Time to Visit Ottawa
Frequently asked questions about the climate in Ottawa
What is the best time to visit Ottawa?
July and September typically offer the most optimal weather in Ottawa. In contrast, January, February, March, November and December tend to have less optimal conditions.
What temperatures can I expect in Ottawa?
Daytime highs range from -1°C (30°F) in January to 29°C (84°F) in July. Nighttime lows range from -10°C (14°F) to 18°C (64°F). Temperatures vary considerably through the year.
How much rain does Ottawa get?
Annual rainfall is around 1008 mm (40 in). June is the wettest month with 129 mm (5.1 in), while January is the driest with 46 mm (1.8 in).
Ottawa 3-Day Forecast
Ottawa (IL) 3-Day Forecast
Ottawa on the map
Ottawa is highlighted — select any city to see its climate.
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