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
The start of May is characterized by an increase in the average high-temperature, transitioning from a moderate 56.8°F (13.8°C) in April to a pleasant 68.5°F (20.3°C). The average low-temperature during May nights is a cool 51.6°F (10.9°C).Humidity
The average relative humidity in May in Alton is 69%.Rainfall
In May, the rain falls for 17.2 days. Throughout May, 3.31" (84mm) of precipitation is accumulated. Throughout the year, there are 124 rainfall days, and 24.09" (612mm) of precipitation is accumulated.Snowfall
January through May, October through December are months with snowfall. May is the last month it regularly snows. During 0.2 snowfall days, in May, Alton aggregates 0.2" (5mm) of snow. Throughout the year, there are 49.5 snowfall days, and 18.39" (467mm) of snow is accumulated.Daylight
In Alton, the average length of the day in May is 14h and 41min.On the first day of May, sunrise is at 6:16 am and sunset at 8:25 pm. On the last day of the month, sunrise is at 5:47 am and sunset at 8:56 pm CDT.
Sunshine
In May, the average sunshine is 8.5h.UV index
The average daily maximum UV index in May is 5. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for the ordinary person.Note: The maximum daily UV index of 5 in May interprets into the following recommendations:
Guard yourself - An obligation to protect skin and eyes from harm exists. Exposing oneself to the midday Sun can be harmful due to the strong UV radiation; limit your time outside. Arm yourself against UV rays' harm with protective apparel and UV-filtering shades. Remember! The Sun's UV radiation can be magnified almost twofold by the reflection of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in May?
What is the average humidity in May?
How many days does it rain in May?
What is the last month it snows?
How many hours of daylight does Alton have in May?
What time are sunrise and sunset in May?
How long on average sun shines in May in Alton?
How high is the UV index in May?
Average temperature in May
Alton, IA
- Average high temperature in May: 68.5°F
The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (24.6°F).
- Average low temperature in May: 51.6°F
The month with the highest average low temperature is July (63.3°F).
The coldest month (with the lowest average low temperature) is January (11.3°F).
Average pressure in May
Alton, IA
- Average pressure in May: 29.92"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).
Average wind speed in May
Alton, IA
- Average wind speed in May: 9.8mph
The windiest month (with the highest average wind speed) is April (11.3mph).
The calmest month (with the lowest average wind speed) is July (7.8mph).
Average humidity in May
Alton, IA
- Average humidity in May: 69%
The month with the highest relative humidity is January (86%).
The month with the lowest relative humidity is October (67%).
Average rainfall in May
Alton, IA
- Average rainfall in May: 3.31"
The wettest month (with the highest rainfall) is June (3.82").
The driest month (with the least rainfall) is January (0.79").
Average rainfall days in May
Alton, IA
- Average rainfall days in May: 17.2 days
The month with the highest number of rainy days is June (18 days).
The month with the least rainy days is February (2.8 days).
Average snowfall in May
Alton, IA
- Average snowfall in May: 0.2"
The month with the highest snowfall is February (4.61").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in May
Alton, IA
- Average snowfall days in May: 0.2 days
The month with the highest number of snowfall days is January (12.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in May /
Average sunshine in May
Alton, IA
- Average daylight in May: 14h and 4min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in May: 8h and 3min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in May
Alton, IA
- Average sunshine days in May: 11.8 days
The month with the most sunshine days is November (20.3 days).
The month with the least sunshine days is June (9.3 days).
Average UV index in May
Alton, IA
- Average UV index in May: 5
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in May
Alton, IA
- Average cloud cover in May: 42
The month with the most cloud cover is January (Cloud cover 56).
The month with the least cloud cover is July (Cloud cover 28).
Average visibility in May
Alton, IA
- Average visibility in May: 6mi
The months with the highest visibility are February, March, April, May, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is January (5mi).
Alton, Iowa, USA
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