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
Royal's weather in December involves a decrease in the average high-temperature, moving down from November's chilly 48.7°F (9.3°C) to an icy 37.6°F (3.1°C). Throughout December, Royal encounters an average temperature drop to a freezing cold 27.5°F (-2.5°C).Humidity
The average relative humidity in December in Royal is 80%.Rainfall
In Royal, in December, during 6.9 rainfall days, 0.71" (18mm) of precipitation is typically accumulated. Throughout the year, there are 121.5 rainfall days, and 13.46" (342mm) of precipitation is accumulated.Snowfall
Months with snowfall in Royal are January through April, November and December. In Royal, in December, during 6.1 snowfall days, 0.83" (21mm) of snow is typically accumulated. Throughout the year, in Royal, there are 26.9 snowfall days, and 3.78" (96mm) of snow is accumulated.Daylight
The month with the shortest days in Royal is December, with an average of 9h and 24min of daylight.On the first day of December in Royal, sunrise is at 6:55 am and sunset at 4:26 pm. On the last day of the month, sunrise is at 7:14 am and sunset at 4:36 pm CST.
Sunshine
In Royal, the average sunshine in December is 4.5h.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index estimate of 2, and below, represents a low health risk from exposure to the Sun's UV rays for average individuals.Note: In December, the UV index of 2 transforms into the following advice:
Infants, children, and people with sensitive skin should always have protection against lengthy periods of sun exposure. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear. Take note! UV radiation from the Sun can double in intensity due to snow reflection.
Frequently asked questions
Is December cold in Royal?
What is the average humidity in December in Royal?
How much does it rain in Royal in December?
How many days does it snow in December in Royal?
What is the month with the shortest days in Royal?
How many hours of daylight does Royal have in December?
What time are sunrise and sunset in December in Royal?
How long on average sun shines in December in Royal?
When is the lowest UV index in Royal?
What is the UV index reading in December in Royal?
Average temperature in December
Royal, IL
- Average high temperature in December: 37.6°F
The warmest month (with the highest average high temperature) is July (81°F).
The month with the lowest average high temperature is January (31.5°F).
- Average low temperature in December: 27.5°F
The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (19.8°F).
Average pressure in December
Royal, IL
- Average pressure in December: 30.12"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
Royal, IL
- Average wind speed in December: 10.1mph
The windiest month (with the highest average wind speed) is January (10.7mph).
The calmest month (with the lowest average wind speed) is August (6.4mph).
Average humidity in December
Royal, IL
- Average humidity in December: 80%
The month with the highest relative humidity is July (85%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Royal, IL
- Average rainfall in December: 0.71"
The wettest month (with the highest rainfall) is May (1.77").
The driest month (with the least rainfall) is February (0.67").
Average rainfall days in December
Royal, IL
- Average rainfall days in December: 6.9 days
The month with the highest number of rainy days is May (14.8 days).
The month with the least rainy days is February (4.6 days).
Average snowfall in December
Royal, IL
- Average snowfall in December: 0.83"
The month with the highest snowfall is February (1.38").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Royal, IL
- Average snowfall days in December: 6.1 days
The month with the highest number of snowfall days is January (7.9 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
Royal, IL
- Average daylight in December: 9h and 2min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in December: 4h and 3min
The month with the most sunshine is June (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in December
Royal, IL
- Average sunshine days in December: 19.4 days
The month with the most sunshine days is November (20.4 days).
The month with the least sunshine days is July (11.3 days).
Average UV index in December
Royal, IL
- Average UV index in December: 2
The months with the highest UV index are 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
Royal, IL
- Average cloud cover in December: 54
The month with the most cloud cover is January (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 31).
Average visibility in December
Royal, IL
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are July and August (5mi).
Royal, Illinois, USA
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