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, Keystone sees a temperature rise, with the average high-temperature moving from April's moderate 57.7°F (14.3°C) to a pleasant 68.7°F (20.4°C). During May, the nighttime temperature averages of 52.2°F (11.2°C).Humidity
In Keystone, the average relative humidity in May is 78%.Rainfall
May is the month with the most rainfall. Rain falls for 18.1 days and accumulates 4.61" (117mm) of precipitation.Snowfall
January through May, October through December are months with snowfall in Keystone. May is the last month it regularly snows. During 0.2 snowfall days, in May, Keystone aggregates 0.12" (3mm) of snow. In Keystone, during the entire year, snow falls for 39 days and aggregates up to 16.69" (424mm) of snow.Daylight
In May, the average length of the day is 14h and 35min.On the first day of the month, sunrise is at 6:03 am and sunset at 8:08 pm. On the last day of May, sunrise is at 5:35 am and sunset at 8:37 pm CDT.
Sunshine
In May, the average sunshine is 8.5h.UV index
In Keystone, the average daily maximum UV index in May is 5. A UV Index reading of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV radiation for ordinary individuals.Note: In May, the maximum UV index of 5 suggests this advice:
Guard yourself - Precautionary measures against sun damage are advocated. Midday Sun has the strongest UV rays, making it crucial to limit exposure and find shade. To cut down UV radiation exposure by about half, sport a wide-brim hat. Keep in mind! Snow's reflective quality can nearly double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average May temperature?
What is the average humidity in May in Keystone?
What is the rainiest month?
How much does it rain in May?
What is the last month it snows?
What is the average length of the day in May?
What time are sunrise and sunset in May?
How many hours of sunshine does Keystone have in May?
What is the UV index intensity in May in Keystone?
Average temperature in May
Keystone, IA
- Average high temperature in May: 68.7°F
The warmest month (with the highest average high temperature) is July (80.8°F).
The month with the lowest average high temperature is January (25.9°F).
- Average low temperature in May: 52.2°F
The month with the highest average low temperature is July (64.4°F).
The coldest month (with the lowest average low temperature) is January (13.5°F).
Average pressure in May
Keystone, IA
- Average pressure in May: 29.94"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed in May
Keystone, IA
- Average wind speed in May: 9.2mph
The windiest month (with the highest average wind speed) is April (10.8mph).
The calmest month (with the lowest average wind speed) is August (7mph).
Average humidity in May
Keystone, IA
- Average humidity in May: 78%
The month with the highest relative humidity is January (85%).
The month with the lowest relative humidity is October (72%).
Average rainfall in May
Keystone, IA
- Average rainfall in May: 4.61"
The wettest month (with the highest rainfall) is May (4.61").
The driest month (with the least rainfall) is January (1.18").
Average rainfall days in May
Keystone, IA
- Average rainfall days in May: 18.1 days
The month with the highest number of rainy days is June (19.3 days).
The month with the least rainy days is January (4.5 days).
Average snowfall in May
Keystone, IA
- Average snowfall in May: 0.12"
The month with the highest snowfall is January (5.24").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in May
Keystone, IA
- Average snowfall days in May: 0.2 days
The month with the highest number of snowfall days is February (10.6 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in May /
Average sunshine in May
Keystone, IA
- Average daylight in May: 14h and 4min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in May: 8h and 3min
The month with the most sunshine is July (Average sunshine: 9h and 54min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in May
Keystone, IA
- Average sunshine days in May: 10.6 days
The month with the most sunshine days is October (19.2 days).
The month with the least sunshine days is June (8.4 days).
Average UV index in May
Keystone, IA
- Average UV index in May: 5
The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January, February, October, November and December (UV index 2).
Average cloud cover in May
Keystone, IA
- Average cloud cover in May: 43
The month with the most cloud cover is January (Cloud cover 57).
The month with the least cloud cover is September (Cloud cover 30).
Average visibility in May
Keystone, IA
- Average visibility in May: 6mi
The months with the highest visibility are February, March, April, May, June, August, September, October, November and December (6mi).
The months with the lowest visibility are January and July (5mi).
Keystone, Iowa, USA
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