O'Fallon
Missouri, USA
Long-term weather forecast
Long-term weather forecast

Monthly weather forecast and climate
O'Fallon, MO

January, like December, in O'Fallon, Missouri, is another cold winter month, with average temperature fluctuating between 23.7°F (-4.6°C) and 37.4°F (3°C). January is the coldest month, with an average high-temperature of 37.4°F (3°C) and an average low-temperature of 23.7°F (-4.6°C). Weather in January »

February, the last month of the winter, in O'Fallon, is another cold month, with average temperature varying between 27°F (-2.8°C) and 41.9°F (5.5°C). In February, the average high-temperature is almost the same as in January - a still wintry 41.9°F (5.5°C). Weather in February »

March, the first month of the spring, in O'Fallon, is a cool month, with temperature in the range of an average high of 54.1°F (12.3°C) and an average low of 37.9°F (3.3°C). In O'Fallon, the average high-temperature in March increases, from a wintry 41.9°F (5.5°C) in February, to a cool 54.1°F (12.3°C). Weather in March »

April is an enjoyable spring month in O'Fallon, Missouri, with average temperature varying between 65.3°F (18.5°C) and 47.3°F (8.5°C). In O'Fallon, Missouri, the average high-temperature increases, from a fresh 54.1°F (12.3°C) in March, to an enjoyable 65.3°F (18.5°C). Weather in April »

May, the last month of the spring, in O'Fallon, is a moderately hot month, with temperature in the range of an average high of 74.5°F (23.6°C) and an average low of 57°F (13.9°C). In O'Fallon, the average high-temperature rises, from a comfortable 65.3°F (18.5°C) in April, to a moderately hot 74.5°F (23.6°C). Weather in May »

The first month of the summer, June, is still a warm month in O'Fallon, Missouri, with average temperature fluctuating between 83.8°F (28.8°C) and 66.2°F (19°C). In June, the average high-temperature rises, from a warm 74.5°F (23.6°C) in May, to a still moderately hot 83.8°F (28.8°C). Weather in June »

July in O'Fallon, Missouri, is a hot summer month, with average temperature fluctuating between 87.1°F (30.6°C) and 68.5°F (20.3°C). The warmest month is July, with an average high-temperature of 87.1°F (30.6°C) and an average low-temperature of 68.5°F (20.3°C). The average heat index is estimated at a torrid 101.5°F (38.6°C). Weather in July »

The last month of the summer, August, is another warm month in O'Fallon, Missouri, with average temperature ranging between min 66.6°F (19.2°C) and max 85.5°F (29.7°C). In August, the average high-temperature is essentially the same as in July - a warm 85.5°F (29.7°C). Weather in August »

The first month of the autumn, September, is still a warm month in O'Fallon, Missouri, with average temperature varying between 60.1°F (15.6°C) and 79.5°F (26.4°C). In O'Fallon, Missouri, the average high-temperature in September marginally drops, from a warm 85.5°F (29.7°C) in August, to a still moderately hot 79.5°F (26.4°C). Weather in September »

October, the same as September, is another comfortable autumn month in O'Fallon, Missouri, with average temperature varying between 48.7°F (9.3°C) and 66.2°F (19°C). In O'Fallon, the average high-temperature drops, from a warm 79.5°F (26.4°C) in September, to a comfortable 66.2°F (19°C). Weather in October »

The last month of the autumn, November, is another cool month in O'Fallon, Missouri, with average temperature fluctuating between 53.2°F (11.8°C) and 37.6°F (3.1°C). In November, the average high-temperature decreases, from an enjoyable 66.2°F (19°C) in October, to a cool 53.2°F (11.8°C). Weather in November »

December, the first month of the winter, in O'Fallon, is also a wintry month, with average temperature ranging between max 41.9°F (5.5°C) and min 30.4°F (-0.9°C). In December, the average high-temperature drops, from a fresh 53.2°F (11.8°C) in November, to a cold 41.9°F (5.5°C). Weather in December »

What is the coldest month in O'Fallon?

The coldest month in O'Fallon is January, with an average high-temperature of 37.4°F (3°C) and an average low-temperature of 23.7°F (-4.6°C).

How many days does it rain in O'Fallon?

Throughout the year, there are 132.3 rainfall days, and 21.06" (535mm) of precipitation is accumulated.

When does it snow in O'Fallon?

Months with snowfall in O'Fallon, Missouri, are January through March, November and December.

How many days does it snow in O'Fallon?

In O'Fallon, Missouri, during the entire year, snow falls for 19 days, and aggregates up to 4.13" (105mm) of snow.

What is the month with the least sunshine in O'Fallon?

January and February, with an average of 4.7h of sunshine, are months with the least sunshine.

When is the lowest UV index in O'Fallon?

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

What is the snowiest month in O'Fallon?

The month with the most snowfall is February when snow falls for 5.8 days and typically aggregates up to 1.61" (41mm) of snow.

When it does not snow in O'Fallon?

April through October are months without snowfall in O'Fallon, Missouri.

What is the most humid month in O'Fallon?

With an average relative humidity of 79%, May is the most humid month in O'Fallon, Missouri.

What is the rainiest month in O'Fallon?

May is the month with the most rainfall in O'Fallon. Rain falls for 15.7 days and accumulates 2.76" (70mm) of precipitation.

What is the month with the highest UV index in O'Fallon?

Months with the highest UV index are May through August, with an average maximum UV index of 6.

When are the longest days in O'Fallon?

June has the longest days of the year in O'Fallon, Missouri, with an average of 14.9h of daylight.

What month has the most sunshine in O'Fallon?

With an average of 10.5h of sunshine, June has the most sunshine of the year.

What is the warmest month in O'Fallon?

With an average high-temperature of 87.1°F (30.6°C) and an average low-temperature of 68.5°F (20.3°C), July is the warmest month in O'Fallon.

What is the least humid month in O'Fallon?

With an average relative humidity of 70%, October is the least humid month in O'Fallon.

What is the driest month in O'Fallon?

December is the month with the least rainfall in O'Fallon. Rain falls for 7 days and accumulates 0.91" (23mm) of precipitation.

What is the month with the shortest days in O'Fallon?

With an average of 9.5h of daylight, December has the shortest days of the year in O'Fallon, Missouri.
Average rainfall - O
Average rainfall days - O

The month with the highest number of rainy days is May (15.7 days).
The month with the least rainy days is February (6.8 days).

Average snowfall - O

The month with the highest snowfall is February (41mm).
Months with the least snowfall are April, May, June, July, August, September and October (0mm).

Average snowfall days - O

Months with the highest number of snowfall days are January and February (5.8 days).
Months with the least snowfall days are May, June, July, August, September and October (0 days).

Average daylight / Average sunshine - O

The month with the longest days is June (Average daylight: 14.9h).
The month with the shortest days is December (Average daylight: 9.5h).

The month with the most sunshine is June (Average sunshine: 10.5h).
Months with the least sunshine are January and February (Average sunshine: 4.7).

Average UV index - O