December weather forecastSaint Marys, IA
December
Weather in December
The first month of the winter, December, is still a cold month in Saint Marys, Iowa, with temperature in the range of an average high of 34.7°F (1.5°C) and an average low of 22.8°F (-5.1°C).Temperature
Saint Marys's average high-temperature decreases in December, falling from a frosty 47.5°F (8.6°C) in November to a wintry 34.7°F (1.5°C). Nighttime temperature dips to a mean of 22.8°F (-5.1°C) during December.Humidity
In December, the average relative humidity is 78%.Rainfall
The month with the least rainfall is December, when the rain falls for 4.7 days and typically collects 0.55" (14mm) of precipitation.Snowfall
January through May, October through December are months with snowfall. In Saint Marys, Iowa, in December, during 5.7 snowfall days, 0.94" (24mm) of snow is typically accumulated. In Saint Marys, Iowa, during the entire year, snow falls for 31.9 days and aggregates up to 10.12" (257mm) of snow.Daylight
December has the shortest days of the year in Saint Marys, with an average of 9h and 18min of daylight.On the first day of December, sunrise is at 7:22 am and sunset at 4:46 pm. On the last day of the month, sunrise is at 7:40 am and sunset at 4:55 pm CST.
Sunshine
In Saint Marys, the average sunshine in December is 4.8h.UV index
In December, the average daily maximum UV index is 2. A UV Index reading of 2, and below, represents a low health risk from unprotected exposure to Sun's UV rays for ordinary individuals.Note: In December, a regular UV index of 2 translates into these guidelines:
Extended sun exposure is not an issue for the majority. Children, infants, and fair-skinned individuals always need to be protected. Midday Sun has the strongest UV rays, making it crucial to limit exposure and find shade. Tightly woven clothing, when worn loosely, shields effectively against the Sun. Take careful note! The UV radiation of the Sun can be nearly doubled by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Saint Marys, IA
- Average high temperature in December: 34.7°F
The warmest month (with the highest average high temperature) is July (83.1°F).
The month with the lowest average high temperature is January (28.8°F).
- Average low temperature in December: 22.8°F
The month with the highest average low temperature is July (65.7°F).
The coldest month (with the lowest average low temperature) is January (15.3°F).
Average pressure in December
Saint Marys, IA
- 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 (29.89"Hg).
Average wind speed in December
Saint Marys, IA
- Average wind speed in December: 9.9mph
The windiest month (with the highest average wind speed) is January (10.4mph).
The calmest month (with the lowest average wind speed) is August (6.9mph).
Average humidity in December
Saint Marys, IA
- Average humidity in December: 78%
The months with the highest relative humidity are January and June (82%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Saint Marys, IA
- Average rainfall in December: 0.55"
The wettest month (with the highest rainfall) is May (3.07").
The driest month (with the least rainfall) is December (0.55").
Average rainfall days in December
Saint Marys, IA
- Average rainfall days in December: 4.7 days
The months with the highest number of rainy days are May and June (15.9 days).
The month with the least rainy days is January (3.4 days).
Average snowfall in December
Saint Marys, IA
- Average snowfall in December: 0.94"
The month with the highest snowfall is February (3.03").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Saint Marys, IA
- Average snowfall days in December: 5.7 days
The month with the highest number of snowfall days is January (9.7 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Saint Marys, IA
- Average daylight in December: 9h and 18min
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 18min).
- Average sunshine in December: 4h and 48min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 18min).
Average sunshine days in December
Saint Marys, IA
- Average sunshine days in December: 21.9 days
The month with the most sunshine days is December (21.9 days).
The month with the least sunshine days is June (11 days).
Average UV index in December
Saint Marys, IA
- Average UV index in December: 2
The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in December
Saint Marys, IA
- Average cloud cover in December: 49
The month with the most cloud cover is January (Cloud cover 53).
The month with the least cloud cover is July (Cloud cover 28).
Average visibility in December
Saint Marys, IA
- 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).
