Contents
- Weather in May
- Frequently asked questions
- Average temperature in May
- Average pressure in May
- Average wind speed in May
- Average humidity in May
- Average rainfall in May
- Average rainfall days in May
- Average snowfall in May
- Average snowfall days in May
- Average daylight in May
- Average sunshine in May
- Average sunshine days in May
- Average UV index in May
- Average cloud cover in May
- Average visibility in May
Weather in May
Temperature
With the onset of May, O'Fallon's weather sees a temperature rise, transitioning from a comfortable 64.9°F (18.3°C) in April to a warm 74.8°F (23.8°C). O'Fallon encounters a steady low-temperature average of 57.9°F (14.4°C) throughout the month of May.Humidity
The months with the highest humidity in O'Fallon are May, July and August, with an average relative humidity of 79%.Rainfall
In O'Fallon, Illinois, in May, during 12.8 rainfall days, 1.34" (34mm) of precipitation is typically accumulated. In O'Fallon, Illinois, during the entire year, the rain falls for 108.8 days and collects up to 10.24" (260mm) of precipitation.Snowfall
April through October are months without snowfall.Daylight
In May, the average length of the day is 14h and 17min.On the first day of the month, sunrise is at 6:01 am and sunset at 7:52 pm. On the last day of May, in O'Fallon, Illinois, sunrise is at 5:37 am and sunset at 8:17 pm CDT.
Sunshine
In May, the average sunshine is 9.3h.UV index
The months with the highest UV index in O'Fallon are May through August, with an average maximum UV index of 6. A UV Index reading of 6 to 7 represents a high health hazard from unsafe exposure to UV radiation for ordinary individuals.Note: The UV index of 6 during May translates into the following guidance:
Uphold preventive measures and conform to sun safety guidelines. Defending against skin and eye harm is crucial. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. For effective sun eye protection, rely on sunglasses certified for UVA and UVB resistance.
Frequently asked questions
What are the temperatures in O'Fallon in May?
What are the most humid months in O'Fallon?
What is the average humidity in May in O'Fallon?
How many days does it rain in May in O'Fallon?
When it does not snow in O'Fallon?
What is the average length of the day in May in O'Fallon?
When is the sunrise / sunset in May in O'Fallon?
How long on average sun shines in May in O'Fallon?
When is the highest UV index in O'Fallon?
How high is the UV index in May in O'Fallon?
Average temperature in May
O'Fallon, IL
- Average high temperature in May: 74.8°F
The warmest month (with the highest average high temperature) is July (85.6°F).
The month with the lowest average high temperature is January (37.8°F).
- Average low temperature in May: 57.9°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 (24.6°F).
Average pressure in May
O'Fallon, IL
- Average pressure in May: 29.96"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in May
O'Fallon, IL
- Average wind speed in May: 7.5mph
The windiest month (with the highest average wind speed) is January (9.5mph).
The calmest month (with the lowest average wind speed) is July (5.6mph).
Average humidity in May
O'Fallon, IL
- Average humidity in May: 79%
The months with the highest relative humidity are May, July and August (79%).
The month with the lowest relative humidity is October (70%).
Average rainfall in May
O'Fallon, IL
- Average rainfall in May: 1.34"
The wettest month (with the highest rainfall) is July (1.42").
The driest month (with the least rainfall) is December (0.31").
Average rainfall days in May
O'Fallon, IL
- Average rainfall days in May: 12.8 days
The month with the highest number of rainy days is July (13.1 days).
The month with the least rainy days is December (4.6 days).
Average snowfall in May
O'Fallon, IL
- Average snowfall in May: 0"
The month with the highest snowfall is January (0.51").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in May
O'Fallon, IL
- Average snowfall days in May: 0 days
The month with the highest number of snowfall days is January (4.7 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in May /
Average sunshine in May
O'Fallon, IL
- Average daylight in May: 14h and 2min
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 May: 9h and 2min
The months with the most sunshine are June and July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 30min).
Average sunshine days in May
O'Fallon, IL
- Average sunshine days in May: 15.5 days
The month with the most sunshine days is December (23.6 days).
The months with the least sunshine days are May and July (15.5 days).
Average UV index in May
O'Fallon, IL
- Average UV index in May: 6
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 May
O'Fallon, IL
- Average cloud cover in May: 38
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 May
O'Fallon, IL
- Average visibility in May: 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'Fallon, Illinois, USA
Weather forecast for your location
2. Allow the app to use your location
