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
As Johnston transitions into May, a rise in the average high-temperature is observed, moving from a moderate 59.4°F (15.2°C) in April to an agreeable 69.6°F (20.9°C). In Johnston, an average temperature of 52.9°F (11.6°C) is noted during May nights.Humidity
In May, the average relative humidity is 77%.Rainfall
The months with the most rainfall are May and June, with an average 2.52" (64mm) of precipitation.Snowfall
Months with snowfall are January through May, October through December. May is the last month it regularly snows. During 0.2 snowfall days, in May, Johnston aggregates 0.08" (2mm) of snow. In Johnston, during the entire year, snow falls for 29.6 days and aggregates up to 6.77" (172mm) of snow.Daylight
In Johnston, the average length of the day in May is 14h and 33min.On the first day of the month, sunrise is at 6:10 am and sunset at 8:13 pm. On the last day of May, sunrise is at 5:42 am and sunset at 8:42 pm CDT.
Sunshine
The average sunshine in May is 8.8h.UV index
The average daily maximum UV index in May is 5. A UV Index reading of 3 to 5 represents a medium vulnerability from unsafe exposure to UV radiation for the average person.Note: The daily maximum UV index of 5 in May interprets into the following advice:
Adopt protective measures - It is advised to guard against sun damage. UV radiation is strongest from the Sun during midday; protect yourself by staying in shaded areas. To best shield against UV radiation, choose sun-safe garments and dependable sunglasses. Keep in mind! Snow's reflective quality can nearly double the intensity of the Sun's UV radiation.
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Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Johnston in May?
What is the average humidity in May?
What is the wettest month?
How much does it rain in May?
What is the last month it snows?
How many hours of daylight does Johnston have in May?
When is the sunrise / sunset in May?
How long on average sun shines in May?
How high is the UV index in May?
Average temperature in May
Johnston, IA
- Average high temperature in May: 69.6°F
The warmest month (with the highest average high temperature) is July (82.4°F).
The month with the lowest average high temperature is January (27.9°F).
- Average low temperature in May: 52.9°F
The month with the highest average low temperature is July (65.1°F).
The coldest month (with the lowest average low temperature) is January (14.4°F).
Average pressure in May
Johnston, IA
- Average pressure in May: 29.93"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in May
Johnston, IA
- Average wind speed in May: 8.8mph
The windiest month (with the highest average wind speed) is April (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (7mph).
Average humidity in May
Johnston, IA
- Average humidity in May: 77%
The month with the highest relative humidity is January (83%).
The month with the lowest relative humidity is October (70%).
Average rainfall in May
Johnston, IA
- Average rainfall in May: 2.52"
The wettest months (with the highest rainfall) are May and June (2.52").
The driest month (with the least rainfall) is January (0.47").
Average rainfall days in May
Johnston, IA
- Average rainfall days in May: 16.3 days
The month with the highest number of rainy days is May (16.3 days).
The month with the least rainy days is February (3.5 days).
Average snowfall in May
Johnston, IA
- Average snowfall in May: 0.08"
The month with the highest snowfall is January (2.2").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in May
Johnston, IA
- Average snowfall days in May: 0.2 days
The month with the highest number of snowfall days is January (8.4 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in May /
Average sunshine in May
Johnston, 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 5min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 18min).
Average sunshine days in May
Johnston, IA
- Average sunshine days in May: 12.5 days
The month with the most sunshine days is December (22.8 days).
The month with the least sunshine days is June (11.2 days).
Average UV index in May
Johnston, IA
- Average UV index in May: 5
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in May
Johnston, IA
- Average cloud cover in May: 40
The month with the most cloud cover is January (Cloud cover 53).
The month with the least cloud cover is September (Cloud cover 28).
Average visibility in May
Johnston, IA
- Average visibility in May: 6mi
The months with the highest visibility are January, February, March, April, May, June, August, September, October, November and December (6mi).
The month with the lowest visibility is July (5mi).
Johnston, Iowa, USA
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