Monthly weather forecast and climate
Boulder, CO

The old building of the University of Colorado in Boulder, Colorado
The old building of the University of Colorado in Boulder, Colorado

Weather in January

January, like December, in Boulder, Colorado, is a wintry winter month, with temperature in the range of an average low of 19°F (-7.2°C) and an average high of 36.7°F (2.6°C). In Boulder, Colorado, the average high-temperature is almost the same as in December - a still cold 36.7°F (2.6°C). Weather in January »

Weather in February

February, the last month of the winter, in Boulder, is another cold month, with average temperature fluctuating between 18°F (-7.8°C) and 36.1°F (2.3°C). In Boulder, the average high-temperature is essentially the same as in January - a still wintry 36.1°F (2.3°C). Weather in February »

Weather in March

March, the first month of the spring, in Boulder, is a frosty month, with average temperature varying between 26.1°F (-3.3°C) and 46.4°F (8°C). In March, the average high-temperature increases, from a cold 36.1°F (2.3°C) in February, to a chilly 46.4°F (8°C). Weather in March »

Weather in April

April is a cool spring month in Boulder, Colorado, with temperature in the range of an average low of 30.7°F (-0.7°C) and an average high of 52.3°F (11.3°C). In Boulder, the average high-temperature in April slightly increases, from a chilly 46.4°F (8°C) in March, to a fresh 52.3°F (11.3°C). Weather in April »

Weather in May

May, the last month of the spring, in Boulder, is an enjoyable month, with average temperature fluctuating between 61°F (16.1°C) and 38.7°F (3.7°C). In May, the average high-temperature marginally rises, from a fresh 52.3°F (11.3°C) in April, to an enjoyable 61°F (16.1°C). Weather in May »

Weather in June

June, the first month of the summer, in Boulder, is a moderately hot month, with average temperature fluctuating between 50°F (10°C) and 76.6°F (24.8°C). In Boulder, Colorado, the average high-temperature significantly increases, from a comfortable 61°F (16.1°C) in May, to a moderately hot 76.6°F (24.8°C). Weather in June »

Weather in July

July, like June, in Boulder, Colorado, is another warm summer month, with temperature in the range of an average low of 55.2°F (12.9°C) and an average high of 80.4°F (26.9°C). The warmest month is July, with an average high-temperature of 80.4°F (26.9°C) and an average low-temperature of 55.2°F (12.9°C). Weather in July »

Weather in August

August, the last month of the summer, in Boulder, is another warm month, with average temperature fluctuating between 54.1°F (12.3°C) and 79.5°F (26.4°C). In August, the average high-temperature is almost the same as in July - a still warm 79.5°F (26.4°C). Weather in August »

Weather in September

The first month of the autumn, September, is also an agreeable month in Boulder, Colorado, with average temperature ranging between max 72.3°F (22.4°C) and min 47.8°F (8.8°C). In Boulder, the average high-temperature slightly decreases, from a warm 79.5°F (26.4°C) in August, to an agreeable 72.3°F (22.4°C). Weather in September »

Weather in October

October, the same as September, in Boulder, Colorado, is another mild autumn month, with average temperature ranging between max 57.2°F (14°C) and min 35.2°F (1.8°C). In Boulder, the average high-temperature plummets, from an agreeable 72.3°F (22.4°C) in September, to a mild 57.2°F (14°C). Weather in October »

Weather in November

November, the last month of the autumn, in Boulder, is another chilly month, with temperature in the range of an average high of 46°F (7.8°C) and an average low of 26.4°F (-3.1°C). In November, the average high-temperature drops, from a moderate 57.2°F (14°C) in October, to a frosty 46°F (7.8°C). Weather in November »

Weather in December

December, the first month of the winter, in Boulder, is also a wintry month, with average temperature fluctuating between 35.2°F (1.8°C) and 18.1°F (-7.7°C). The coldest month is December, with an average high-temperature of 35.2°F (1.8°C) and an average low-temperature of 18.1°F (-7.7°C). Weather in December »
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FAQ

How many days does it rain in Boulder?

In Boulder, during the entire year, the rain falls for 117.3 days and collects up to 14.17" (360mm) of precipitation.

What is the driest month in Boulder?

January is the month with the least rainfall in Boulder, Colorado. Rain falls for 4.3 days and accumulates 0.39" (10mm) of precipitation.

When does it snow in Boulder?

Months with snowfall in Boulder, Colorado, are January through May, October through December.

How many days does it snow in Boulder?

Throughout the year, in Boulder, there are 44.8 snowfall days, and 37.01" (940mm) of snow is accumulated.

When is the lowest UV index in Boulder?

Months with the lowest UV index in Boulder are January, February, November and December, with an average maximum UV index of 2.

What is the most humid month in Boulder?

With an average relative humidity of 70%, February is the most humid month in Boulder.

What is the month with the least sunshine in Boulder?

With an average of 6.6h of sunshine, February has the least sunshine of the year.

What is the snowiest month in Boulder?

April is the month with the most snowfall. Snow falls for 4.9 days and accumulates 7.76" (197mm) of snow.

What is the wettest month in Boulder?

May is the month with the most rainfall. Rain falls for 17.5 days and accumulates 2.48" (63mm) of precipitation.

What is the least humid month in Boulder?

June, August and September, with an average relative humidity of 45%, are the least humid months.

When it does not snow in Boulder?

June through September are months without snowfall.

When are the longest days in Boulder?

June has the longest days of the year, with an average of 15h of daylight.

What is the month with the most sunshine in Boulder?

June and July, with an average of 11.7h of sunshine, are months with the most sunshine.

What are the months with the highest UV index in Boulder?

Months with the highest UV index in Boulder are June through August, with an average maximum UV index of 5.

What is the warmest month in Boulder?

The warmest month in Boulder, Colorado, is July, with an average high-temperature of 80.4°F (26.9°C) and an average low-temperature of 55.2°F (12.9°C).

What is the coldest month in Boulder?

The coldest month is December, with an average high-temperature of 35.2°F (1.8°C) and an average low-temperature of 18.1°F (-7.7°C).

What is the month with the shortest days in Boulder?

The month with the shortest days in Boulder is December, with an average of 9.4h of daylight.

Average pressure
Boulder, CO

Average pressure - Boulder, CO

The month with the highest atmospheric pressure is January (30.15").
Months with the lowest atmospheric pressure are April, May and June (29.92").

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Average wind speed
Boulder, CO

Average wind speed - Boulder, CO

The windiest month (with the highest average wind speed) is January (7.3mph).
The calmest months (with the lowest average wind speed) are May, July, August and September (5.7mph).

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Average humidity
Boulder, CO

Average humidity - Boulder, CO

The month with the highest relative humidity is February (70%).
Months with the lowest relative humidity are June, August and September (45%).

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Average rainfall
Boulder, CO

Average rainfall - Boulder, CO

The wettest month (with the highest rainfall) is May (2.48").
The driest month (with the least rainfall) is January (0.39").

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Average rainfall days
Boulder, CO

Average rainfall days - Boulder, CO

The month with the highest number of rainy days is July (17.8 days).
The month with the least rainy days is November (3.3 days).

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Average snowfall
Boulder, CO

Average snowfall - Boulder, CO

The month with the highest snowfall is April (7.76").
Months with the least snowfall are June, July, August and September (0").

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Average snowfall days
Boulder, CO

Average snowfall days - Boulder, CO

The month with the highest number of snowfall days is February (10.3 days).
Months with the least snowfall days are June, July and August (0 days).

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Average daylight / Average sunshine
Boulder, CO

Average daylight / Average sunshine - Boulder, CO

The month with the longest days is June (Average daylight: 15h).
The month with the shortest days is December (Average daylight: 9.4h).

Months with the most sunshine are June and July (Average sunshine: 11.7h).
The month with the least sunshine is February (Average sunshine: 6.6h).

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Average sunshine days
Boulder, CO

Average sunshine days - Boulder, CO

The month with the most sunshine days is January (22.2 days).
The month with the least sunshine days is July (9.9 days).

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Average UV index
Boulder, CO

Average UV index - Boulder, CO

Months with the highest UV index are June, July and August (UV index 5).
Months with the lowest UV index are January, February, November and December (UV index 2).

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Average visibility
Boulder, CO

Average visibility - Boulder, CO

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

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