January weather forecast
O'Fallon, MO

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Weather in January

January in O'Fallon, Missouri is characterized by a blanket of white courtesy of the snowfall and colder temperatures playing peek-a-boo. Though a smidge warmer than the anticipated starkness of winter, it poses a significant dip from the milder climes of December. The days are surprisingly short, with limited hours of daylight and sunshine. There is a humidity level that lends a chilly tone to the day, further amplified by an occasional gust of chilly winds. Strikingly, it's the month with the highest snowfall recording at 0.98" (25mm).

Temperature

O'Fallon reaches its lowest average temperatures in January, measuring 37.4°F (3°C) at the peak and 23.7°F (-4.6°C) at the lowest.

Humidity

The average relative humidity in January in O'Fallon is 75%.

Rainfall

In O'Fallon, in January, during 7.2 rainfall days, 1.14" (29mm) of precipitation is typically accumulated. Throughout the year, there are 132.3 rainfall days, and 21.06" (535mm) of precipitation is accumulated.

Snowfall

January through March, November and December are months with snowfall in O'Fallon. In January, it is snowing for 5.8 days. Throughout January, 0.98" (25mm) of snow is accumulated. In O'Fallon, Missouri, during the entire year, snow falls for 19 days and aggregates up to 4.13" (105mm) of snow.

Daylight

The average length of the day in January is 9h and 49min.
On the first day of January in O'Fallon, sunrise is at 7:21 am and sunset at 4:51 pm. On the last day of the month, sunrise is at 7:09 am and sunset at 5:22 pm CST.

Sunshine

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

UV index

The months with the lowest UV index in O'Fallon, Missouri, are January, February, November and December, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a minimal health hazard from unsafe exposure to UV radiation for average individuals.
Note: In January, an average UV index of 2 transforms into the following instructions:
While most individuals can withstand prolonged sun exposure, it is imperative that babies, children, and those with sensitive skin always be shielded. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. Combat UV radiation's detrimental effects with sun-safe clothing and UV-blocking eyewear. Take note! UV radiation from the Sun can double in intensity due to snow reflection.
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Frequently asked questions

What are the coldest months in O'Fallon?

The lowest temperatures in O'Fallon, Missouri, are recorded in January, with averages reaching a high of 37.4°F (3°C) and a low of 23.7°F (-4.6°C).

How cold is January in O'Fallon?

During January, O'Fallon experiences an average high-temperature of 37.4°F (3°C) and a low-temperature of 23.7°F (-4.6°C).

What is the average humidity in January in O'Fallon?

The average relative humidity in January is 75%.

How many days does it rain in January in O'Fallon?

In O'Fallon, Missouri, in January, it is raining for 7.2 days, with typically 1.14" (29mm) of accumulated precipitation.

How much does it snow in O'Fallon in January?

In O'Fallon, during January, snow falls for 5.8 days and regularly aggregates up to 0.98" (25mm) of snow.

What is the average length of the day in January in O'Fallon?

In January, the average day length is 9h and 49min.

When is the sunrise / sunset in January in O'Fallon?

On the first day of January in O'Fallon, Missouri, sunrise is at 7:21 am and sunset at 4:51 pm. On the last day of the month, sunrise is at 7:09 am and sunset at 5:22 pm CST.

What are the months with the least sunshine in O'Fallon?

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

How many hours of sunshine does O'Fallon have in January?

The average sunshine duration in January in O'Fallon is 4.7h.

When is the lowest UV index in O'Fallon?

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

What is the UV index reading in January in O'Fallon?

In January, the average daily maximum UV index in O'Fallon is 2. A UV Index estimate of 2, and below, represents a low health risk from unprotected exposure to UV radiation.
Today
Tomorrow
Long-term
YearJanuaryFMAMJJASOND
Dec
January
Feb
Average high temperature
41.9°F 5.5°C
37.4°F 3°C
41.9°F 5.5°C
Average low temperature
30.4°F -0.9°C
23.7°F -4.6°C
27°F -2.8°C
Average pressure
30.13" 765mmHg
30.16" 766mmHg
30.12" 765mmHg
Average wind speed
8.6mph 13.8km/h
9.1mph 14.6km/h
9mph 14.5km/h
Average max. wind speed
9.1mph 14.6km/h
9.6mph 15.4km/h
9.5mph 15.3km/h
Average wind speed gusts
13.5mph 21.7km/h
14.4mph 23.2km/h
14.2mph 22.9km/h
Average humidity
76%
75%
76%
Average rainfall
0.91" 23mm
1.14" 29mm
1.06" 27mm
Average rainfall days
7
7.2
6.8
Average snowfall
0.67" 17mm
0.98" 25mm
1.61" 41mm
Average snowfall days
3.9
5.8
5.8
Average daylight
9h 3min
9h 5min
10h 5min
Average sunshine
4h 5min
4h 4min
4h 4min
Average sunshine days
20.6
20.4
15.8
Average UV index
2
2
2
Average cloud cover
47%
50%
49%
Average visibility
6mi 9.7km
6mi 9.7km
6mi 9.7km

Average temperature in January
O'Fallon, MO

Average temperature in January - O
  • Average high temperature in January: 37.4°F

The warmest month (with the highest average high temperature) is July (87.1°F).
The month with the lowest average high temperature is January (37.4°F).

  • Average low temperature in January: 23.7°F

The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (23.7°F).

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Average pressure in January
O'Fallon, MO

Average pressure in January - O
  • Average pressure in January: 30.16"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

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Average wind speed in January
O'Fallon, MO

Average wind speed in January - O
  • Average wind speed in January: 9.1mph

The windiest month (with the highest average wind speed) is January (9.1mph).
The calmest month (with the lowest average wind speed) is July (5.5mph).

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Average humidity in January
O'Fallon, MO

Average humidity in January - O
  • Average humidity in January: 75%

The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (70%).

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Average rainfall in January
O'Fallon, MO

Average rainfall in January - O
  • Average rainfall in January: 1.14"

The wettest month (with the highest rainfall) is May (2.76").
The driest month (with the least rainfall) is December (0.91").

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Average rainfall days in January
O'Fallon, MO

Average rainfall days in January - O
  • Average rainfall days in January: 7.2 days

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).

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Average snowfall in January
O'Fallon, MO

Average snowfall in January - O
  • Average snowfall in January: 0.98"

The month with the highest snowfall is February (1.61").
The months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days in January
O'Fallon, MO

Average snowfall days in January - O
  • Average snowfall days in January: 5.8 days

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

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Average daylight in January /
Average sunshine in January
O'Fallon, MO

Average daylight in January / Average sunshine in January - O
  • Average daylight in January: 9h and 5min

The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).

  • Average sunshine in January: 4h and 4min

The month with the most sunshine is June (Average sunshine: 10h and 30min).
The months with the least sunshine are January and February (Average sunshine: 4h and 42min).

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Average sunshine days in January
O'Fallon, MO

Average sunshine days in January - O
  • Average sunshine days in January: 20.4 days

The month with the most sunshine days is December (20.6 days).
The month with the least sunshine days is July (12.6 days).

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Average UV index in January
O'Fallon, MO

Average UV index in January - O
  • Average UV index in January: 2

The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

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Average cloud cover in January
O'Fallon, MO

Average cloud cover in January - O
  • Average cloud cover in January: 50

The month with the most cloud cover is January (Cloud cover 50).
The months with the least cloud cover are June, July, August and September (Cloud cover 28).

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Average visibility in January
O'Fallon, MO

Average visibility in January - O
  • Average visibility in January: 6mi

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

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O'Fallon, Missouri, USA

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