Climate and monthly weather forecast
Ottawa, IL

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Weather in January

January, like December, is another subzero cold winter month in Ottawa, Illinois, with an average temperature varying between 29.1°F (-1.6°C) and 17.2°F (-8.2°C). The coldest temperatures occur during January, when averages reach a peak of 29.1°F (-1.6°C) and a low of 17.2°F (-8.2°C). Weather in January »

Weather in February

February, the last month of the winter in Ottawa, is a cold month, with an average temperature fluctuating between 33.4°F (0.8°C) and 20.7°F (-6.3°C). With February's advent, Ottawa, Illinois, sees an average high-temperature of a cold 33.4°F (0.8°C), subtly shifted from January's 29.1°F (-1.6°C). Weather in February »

Weather in March

The first month of the spring, March, is a frosty month in Ottawa, Illinois, with an average temperature fluctuating between 32.4°F (0.2°C) and 46.9°F (8.3°C). With the onset of March, Ottawa sees a temperature rise, with the average high-temperature moving from February's wintry 33.4°F (0.8°C) to a frosty 46.9°F (8.3°C). Weather in March »

Weather in April

April is a refreshing spring month in Ottawa, Illinois, with an average temperature varying between 42.4°F (5.8°C) and 58.8°F (14.9°C). As Ottawa transitions into April, the average high-temperature shows a change, moving from a frosty 46.9°F (8.3°C) in March to a moderate 58.8°F (14.9°C). Weather in April »

Weather in May

May, the last month of the spring in Ottawa, is an agreeable month, with an average temperature ranging between min 53.6°F (12°C) and max 70.7°F (21.5°C). The arrival of May signals an increase in the average high-temperature, moving from a moderate 58.8°F (14.9°C) in April to an agreeable 70.7°F (21.5°C). Weather in May »

Weather in June

The first month of the summer, June, is a warm month in Ottawa, Illinois, with temperature in the range of an average high of 78.8°F (26°C) and an average low of 61.5°F (16.4°C). Ottawa in June observes a minor temperature shift, with average high-temperatures adjusting from a pleasant 70.7°F (21.5°C) in May to a moderately hot 78.8°F (26°C). Weather in June »

Weather in July

July, the same as June, is a moderately hot summer month in Ottawa, Illinois, with an average temperature fluctuating between 81°F (27.2°C) and 64.2°F (17.9°C). July tends to be the warmest month, with temperatures averaging a daily high of 81°F (27.2°C) and a low of 64.2°F (17.9°C). For most parts of July, the heat index is appraised at a tropical 87.8°F (31°C). Weather in July »

Weather in August

The last month of the summer, August, is also a moderately hot month in Ottawa, Illinois, with an average temperature fluctuating between 79.3°F (26.3°C) and 62.1°F (16.7°C). In Ottawa, August's average high-temperature stands at a still moderately hot 79.3°F (26.3°C), closely related to the preceding month. Weather in August »

Weather in September

The first month of the autumn, September, is also a moderately hot month in Ottawa, Illinois, with temperature in the range of an average low of 56.1°F (13.4°C) and an average high of 74.5°F (23.6°C). As September unfolds, the average high-temperature reaches a still warm 74.5°F (23.6°C), hinting at a slight fluctuation from the previous month. Weather in September »

Weather in October

October, the same as September, is another comfortable autumn month in Ottawa, Illinois, with an average temperature fluctuating between 61.7°F (16.5°C) and 45.7°F (7.6°C). During the transition into October, Ottawa observes a decrease in the average high-temperature, falling from a warm 74.5°F (23.6°C) in September to an enjoyable 61.7°F (16.5°C). Weather in October »

Weather in November

The last month of the autumn, November, is another chilly month in Ottawa, Illinois, with an average temperature ranging between max 47.1°F (8.4°C) and min 33.8°F (1°C). A notable decrease in the average high-temperature is observed during November, falling from a comfortable 61.7°F (16.5°C) in October to a chilly 47.1°F (8.4°C). Weather in November »

Weather in December

The first month of the winter, December, is also a wintry month in Ottawa, Illinois, with an average temperature varying between 25°F (-3.9°C) and 35.1°F (1.7°C). A shift in Ottawa's weather is observed as November turns into December, with the average high temperature reducing from a chilly 47.1°F (8.4°C) to an icy 35.1°F (1.7°C). Weather in December »
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Frequently asked questions

What month is the coldest in Ottawa?

January tends to be the coldest month, with temperatures averaging a daily high of 29.1°F (-1.6°C) and a low of 17.2°F (-8.2°C).

How much does it rain in Ottawa?

In Ottawa, Illinois, during the entire year, the rain falls for 166.3 days and collects up to 35.35" (898mm) of precipitation.

When does it snow in Ottawa?

January through April, October through December are months with snowfall.

How much does it snow in Ottawa?

Throughout the year, there are 43.4 snowfall days, and 17.76" (451mm) of snow is accumulated.

What is the month with the least sunshine in Ottawa?

The month with the least sunshine in Ottawa is January, with an average of 3.9h of sunshine.

When is the lowest UV index in Ottawa?

January and December, with an average maximum UV index of 1, are months with the lowest UV index.

What is the snowiest month in Ottawa?

February is the month with the most snowfall in Ottawa. Snow falls for 10.4 days and accumulates 5.08" (129mm) of snow.

When is Daylight Saving Time (DST) in Ottawa?

On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from CST to CDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from CDT to CST.

What is the rainiest month in Ottawa?

The month with the most rainfall in Ottawa, Illinois, is May, when the rain falls for 19.4 days and typically aggregates up to 5" (127mm) of precipitation.

When it does not snow in Ottawa?

May through September are months without snowfall in Ottawa.

When are the longest days in Ottawa?

The month with the longest days in Ottawa is June, with an average of 15h and 6min of daylight.

What month has the most sunshine in Ottawa?

With an average of 9.8h of sunshine, June has the most sunshine of the year in Ottawa.

What is the month with the highest UV index in Ottawa?

June and July, with an average maximum UV index of 6, are months with the highest UV index in Ottawa.

What time of the year is the hottest in Ottawa?

The warmest month in Ottawa, Illinois, is July, with an average high-temperature of 81°F (27.2°C) and an average low-temperature of 64.2°F (17.9°C).

What is the most humid month in Ottawa?

The most humid month in Ottawa is July, with an average relative humidity of 85%.

What is the least humid month in Ottawa?

With an average relative humidity of 72%, October is the least humid month in Ottawa, Illinois.

What is the driest month in Ottawa?

The month with the least rainfall in Ottawa is November, when the rain falls for 10.2 days and typically collects 1.81" (46mm) of precipitation.

What is the month with the shortest days in Ottawa?

With an average of 9h and 12min of daylight, December has the shortest days of the year.

Average temperature
Ottawa, IL

Average temperature - Ottawa, IL

The warmest month (with the highest average high temperature) is July (81°F).
The month with the lowest average high temperature is January (29.1°F).

The month with the highest average low temperature is July (64.2°F).
The coldest month (with the lowest average low temperature) is January (17.2°F).

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Average pressure
Ottawa, IL

Average pressure - Ottawa, IL

The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

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Average wind speed
Ottawa, IL

Average wind speed - Ottawa, IL

The windiest month (with the highest average wind speed) is April (10.2mph).
The calmest month (with the lowest average wind speed) is August (6.2mph).

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Average rainfall
Ottawa, IL

Average rainfall - Ottawa, IL

The wettest month (with the highest rainfall) is May (5").
The driest month (with the least rainfall) is November (1.81").

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Average rainfall days
Ottawa, IL

Average rainfall days - Ottawa, IL

The month with the highest number of rainy days is July (19.9 days).
The month with the least rainy days is February (6.2 days).

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Average snowfall
Ottawa, IL

Average snowfall - Ottawa, IL

The month with the highest snowfall is February (5.08").
The months with the least snowfall are May, June, July, August and September (0").

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Average snowfall days
Ottawa, IL

Average snowfall days - Ottawa, IL

The month with the highest number of snowfall days is January (12.9 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

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Average daylight / Average sunshine
Ottawa, IL

Average daylight / Average sunshine - Ottawa, IL

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).

The month with the most sunshine is June (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).

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Average sunshine days
Ottawa, IL

Average sunshine days - Ottawa, IL

The month with the most sunshine days is November (17 days).
The month with the least sunshine days is July (7.2 days).

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Average visibility
Ottawa, IL

Average visibility - Ottawa, IL

The months with the highest visibility are March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, February, July and August (5mi).

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Ottawa, Illinois, USA

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