Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average snowfall in December
- Average snowfall days in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
Start of December brings a shift in the average high-temperature, falling from November's cool 52.7°F (11.5°C) to an icy 41.5°F (5.3°C). In Grafton, an average nighttime temperature of 30°F (-1.1°C) is expected during December.Humidity
The average relative humidity in December is 76%.Rainfall
In Grafton, Illinois, during December, the rain falls for 6.8 days and regularly aggregates up to 1.5" (38mm) of precipitation. Throughout the year, there are 138.8 rainfall days, and 27.6" (701mm) of precipitation is accumulated.Snowfall
Months with snowfall are January through March, November and December. In Grafton, Illinois, in December, snow falls for 3.9 days, with typically accumulated 1.14" (29mm) of snow. Throughout the year, in Grafton, there are 17.9 snowfall days, and 5.12" (130mm) of snow is accumulated.Daylight
December has the shortest days of the year in Grafton, Illinois, with an average of 9h and 30min of daylight.On the first day of the month, sunrise is at 7:02 am and sunset at 4:39 pm. On the last day of December, in Grafton, sunrise is at 7:20 am and sunset at 4:49 pm CST.
Sunshine
In Grafton, the average sunshine in December is 4.8h.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Grafton. A UV Index estimate of 2, and below, represents a low health risk from unprotected exposure to Sun's UV rays for average individuals.Note: In December, a regular UV index of 2 translates into these guidelines:
Long-term sun exposure is typically not a concern for most. However, those with sensitive skin, infants, and children must always have protection. Midday is when the Sun's radiation is strongest; avoid prolonged exposure during this time. Stay sun-safe with clothing that is both closely woven and worn loosely. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is December in Grafton?
What is the average humidity in December in Grafton?
How much does it rain in Grafton in December?
How many days does it snow in December in Grafton?
What is the month with the shortest days in Grafton?
What is the average length of the day in December in Grafton?
When is the sunrise / sunset in December in Grafton?
How long on average sun shines in December in Grafton?
When is the lowest UV index in Grafton?
How high is the UV index in December in Grafton?
Average temperature in December
Grafton, IL
- Average high temperature in December: 41.5°F
The warmest month (with the highest average high temperature) is July (86.4°F).
The month with the lowest average high temperature is January (36.1°F).
- Average low temperature in December: 30°F
The month with the highest average low temperature is July (68.2°F).
The coldest month (with the lowest average low temperature) is January (23.4°F).
Average pressure in December
Grafton, IL
- Average pressure in December: 30.13"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).
Average wind speed in December
Grafton, IL
- Average wind speed in December: 8.8mph
The windiest month (with the highest average wind speed) is January (9.4mph).
The calmest months (with the lowest average wind speed) are July and August (5.7mph).
Average humidity in December
Grafton, IL
- Average humidity in December: 76%
The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Grafton, IL
- Average rainfall in December: 1.5"
The wettest month (with the highest rainfall) is May (3.35").
The driest month (with the least rainfall) is February (1.3").
Average rainfall days in December
Grafton, IL
- Average rainfall days in December: 6.8 days
The month with the highest number of rainy days is July (16.3 days).
The month with the least rainy days is January (6.3 days).
Average snowfall in December
Grafton, IL
- Average snowfall in December: 1.14"
The months with the highest snowfall are January and February (1.54").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in December
Grafton, IL
- Average snowfall days in December: 3.9 days
The month with the highest number of snowfall days is January (5.7 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Grafton, IL
- Average daylight in December: 9h and 3min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in December: 4h and 5min
The months with the most sunshine are June and July (Average sunshine: 10h and 24min).
The months with the least sunshine are January and February (Average sunshine: 4h and 36min).
Average sunshine days in December
Grafton, IL
- Average sunshine days in December: 19.8 days
The month with the most sunshine days is December (19.8 days).
The month with the least sunshine days is June (11.2 days).
Average UV index in December
Grafton, IL
- Average UV index in December: 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).
Average cloud cover in December
Grafton, IL
- Average cloud cover in December: 48
The month with the most cloud cover is January (Cloud cover 51).
The month with the least cloud cover is August (Cloud cover 28).
Average visibility in December
Grafton, IL
- 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).
Grafton, Illinois, USA
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