December weather forecast
O'Leary, IA

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Weather in December

The first month of the winter, December, is still a freezing cold month in O'Leary, Iowa, with an average temperature varying between 18.5°F (-7.5°C) and 29.3°F (-1.5°C).

Temperature

In O'Leary, stepping into December signifies a significant temperature decrement, moving down from November's frosty 44.2°F (6.8°C) to a subzero cold 29.3°F (-1.5°C). O'Leary, during the month of December, experiences an average low-temperature of 18.5°F (-7.5°C).

Humidity

The average relative humidity in December is 82%.

Rainfall

In O'Leary, in December, it is raining for 3.4 days, with typically 1.02" (26mm) of accumulated precipitation. Throughout the year, there are 114 rainfall days, and 21.46" (545mm) of precipitation is accumulated.

Snowfall

Months with snowfall in O'Leary are January through April, October through December. In December, in O'Leary, it is snowing for 8.3 days. Throughout December, 1.97" (50mm) of snow is accumulated. Throughout the year, there are 39.2 snowfall days, and 14.84" (377mm) of snow is accumulated.

Daylight

December has the shortest days of the year in O'Leary, with an average of 9h and 6min of daylight.
On the first day of December, sunrise is at 7:35 am and sunset at 4:51 pm. On the last day of the month, sunrise is at 7:54 am and sunset at 5:00 pm CST.

Sunshine

In O'Leary, the average sunshine in December is 4.4h.

UV index

The months with the lowest UV index in O'Leary are January, February, November and December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a minimal health vulnerability from unprotected exposure to Sun's UV rays for the average person.
Note: In December, a daily UV index of 2 turns into the following recommendations:
Infants, children, and people with sensitive skin should always have protection against lengthy periods of sun exposure. Being in direct Sun during midday can be harmful due to intense solar radiation; take precautions. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Notice! The UV radiation of the Sun can be intensified nearly twofold due to the reflective quality of snow.
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold is December in O'Leary?

During December, O'Leary experiences an average high-temperature of 29.3°F (-1.5°C) and a low-temperature of 18.5°F (-7.5°C). The average heat index (a.k.a. 'felt air temperature', 'feels like'), which represents the influence of relative humidity on air temperature, in July is evaluated at 87.8°F (31°C).

What is the average humidity in December in O'Leary?

The average relative humidity in December in O'Leary is 82%.

How much does it rain in O'Leary in December?

In O'Leary, in December, it is raining for 3.4 days, with typically 1.02" (26mm) of accumulated precipitation.

How much does it snow in O'Leary in December?

In O'Leary, in December, snow falls for 8.3 days, with typically accumulated 1.97" (50mm) of snow.

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

December has the shortest days of the year in O'Leary, with an average of 9h and 6min of daylight.

What is the average length of the day in December in O'Leary?

The average day length in December in O'Leary, Iowa, is 9h and 6min.

When are sunrise and sunset in December in O'Leary?

In December, on the first day of the month, sunrise is at 7:35 am and sunset at 4:51 pm. On the last day of the month, sunrise is at 7:54 am and sunset at 5:00 pm CST.

How many hours of sunshine does O'Leary have in December?

The average sunshine duration in December in O'Leary is 4.4h.

When is the lowest UV index in O'Leary?

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

How high is the UV index in December in O'Leary?

In December, the average daily maximum UV index in O'Leary is 2. A UV Index reading of 2, and below, represents a low health threat from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
O'Leary, IA

Average temperature in December - O
  • Average high temperature in December: 29.3°F

The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (24.8°F).

  • Average low temperature in December: 18.5°F

The month with the highest average low temperature is July (64°F).
The coldest month (with the lowest average low temperature) is January (11.5°F).

Average pressure in December
O'Leary, IA

Average pressure in December - O
  • Average pressure in December: 30.12"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).

Average wind speed in December
O'Leary, IA

Average wind speed in December - O
  • Average wind speed in December: 10.4mph

The windiest month (with the highest average wind speed) is April (11.2mph).
The calmest month (with the lowest average wind speed) is July (7.7mph).

Average humidity in December
O'Leary, IA

Average humidity in December - O
  • Average humidity in December: 82%

The month with the highest relative humidity is January (86%).
The month with the lowest relative humidity is October (66%).

Average rainfall in December
O'Leary, IA

Average rainfall in December - O
  • Average rainfall in December: 1.02"

The wettest month (with the highest rainfall) is June (3.35").
The driest month (with the least rainfall) is January (0.63").

Average rainfall days in December
O'Leary, IA

Average rainfall days in December - O
  • Average rainfall days in December: 3.4 days

The month with the highest number of rainy days is June (16.8 days).
The month with the least rainy days is February (2.4 days).

Average snowfall in December
O'Leary, IA

Average snowfall in December - O
  • Average snowfall in December: 1.97"

The month with the highest snowfall is February (4.09").
The months with the least snowfall are May, June, July, August and September (0").

Average snowfall days in December
O'Leary, IA

Average snowfall days in December - O
  • Average snowfall days in December: 8.3 days

The month with the highest number of snowfall days is January (9.2 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average daylight in December /
Average sunshine in December
O'Leary, IA

Average daylight in December / Average sunshine in December - O
  • Average daylight in December: 9h and 1min

The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).

  • Average sunshine in December: 4h and 2min

The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).

Average sunshine days in December
O'Leary, IA

Average sunshine days in December - O
  • Average sunshine days in December: 20.6 days

The month with the most sunshine days is November (22.1 days).
The month with the least sunshine days is June (11.7 days).

Average UV index in December
O'Leary, IA

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

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

Average cloud cover in December
O'Leary, IA

Average cloud cover in December - O
  • Average cloud cover in December: 52

The month with the most cloud cover is January (Cloud cover 55).
The month with the least cloud cover is July (Cloud cover 27).

Average visibility in December
O'Leary, IA

Average visibility in December - O
  • Average visibility in December: 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).

O'Leary, Iowa, USA

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