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 brings a shift in the average high-temperature, increasing from April's refreshing 58.8°F (14.9°C) to an agreeable 69.4°F (20.8°C). Portsmouth's temperature lowers to a mean of 52.9°F (11.6°C) during the nights in May.Humidity
In May, the average relative humidity is 73%.Rainfall
In Portsmouth, in May, during 15.7 rainfall days, 2.6" (66mm) of precipitation is typically accumulated. Throughout the year, there are 113.5 rainfall days, and 15.71" (399mm) of precipitation is accumulated.Snowfall
Months with snowfall are January through May, October through December. May is the last month it regularly snows. During 0.3 snowfall days, in May, Portsmouth aggregates 0.16" (4mm) of snow. In Portsmouth, during the entire year, snow falls for 31.5 days and aggregates up to 7.13" (181mm) of snow.Daylight
The average length of the day in May is 14h and 33min.On the first day of the month, sunrise is at 6:17 am and sunset at 8:20 pm. On the last day of May, sunrise is at 5:50 am and sunset at 8:49 pm CDT.
Sunshine
The average sunshine in May is 8.8h.UV index
In Portsmouth, the average daily maximum UV index in May is 5. A UV Index reading of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for the ordinary person.Note: In May, a regular UV index of 5 translates into these guidelines:
Heed the precautions - It is counselled to guard against solar damage. The Sun's harshest UV rays are around midday; it's wise to seek shade and limit time outdoors. A wide-brimmed hat is a shield, deflecting up to 50% of harmful UV radiation from eyes. Be informed! The Sun's UV radiation can be nearly doubled due to the reflection from snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are May temperatures?
What is the average humidity in May?
How much does it rain in May?
What is the last month it snows in Portsmouth?
What is the average length of the day in May?
When is the sunrise / sunset in May?
How long on average sun shines in May?
What is the UV index reading in May?
Average temperature in May
Portsmouth, IA
- Average high temperature in May: 69.4°F
The warmest month (with the highest average high temperature) is July (82.6°F).
The month with the lowest average high temperature is January (27.3°F).
- Average low temperature in May: 52.9°F
The month with the highest average low temperature is July (64.9°F).
The coldest month (with the lowest average low temperature) is January (14.5°F).
Average pressure in May
Portsmouth, 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 (29.87"Hg).
Average wind speed in May
Portsmouth, IA
- Average wind speed in May: 9.3mph
The windiest month (with the highest average wind speed) is April (10.9mph).
The calmest month (with the lowest average wind speed) is July (7.2mph).
Average humidity in May
Portsmouth, IA
- Average humidity in May: 73%
The month with the highest relative humidity is January (83%).
The month with the lowest relative humidity is October (68%).
Average rainfall in May
Portsmouth, IA
- Average rainfall in May: 2.6"
The wettest month (with the highest rainfall) is June (2.64").
The driest month (with the least rainfall) is January (0.43").
Average rainfall days in May
Portsmouth, IA
- Average rainfall days in May: 15.7 days
The month with the highest number of rainy days is June (16.1 days).
The month with the least rainy days is February (2.8 days).
Average snowfall in May
Portsmouth, IA
- Average snowfall in May: 0.16"
The month with the highest snowfall is February (2.09").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in May
Portsmouth, IA
- Average snowfall days in May: 0.3 days
The month with the highest number of snowfall days is January (8.3 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in May /
Average sunshine in May
Portsmouth, IA
- Average daylight in May: 14h and 4min
The month with the longest days is June (Average daylight: 15h and 6min).
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 30min).
Average sunshine days in May
Portsmouth, IA
- Average sunshine days in May: 12.8 days
The month with the most sunshine days is December (21.6 days).
The month with the least sunshine days is June (11.4 days).
Average UV index in May
Portsmouth, IA
- Average UV index in May: 5
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, October, November and December (UV index 2).
Average cloud cover in May
Portsmouth, IA
- Average cloud cover in May: 40
The month with the most cloud cover is January (Cloud cover 52).
The month with the least cloud cover is July (Cloud cover 27).
Average visibility in May
Portsmouth, IA
- 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).
Portsmouth, Iowa, USA
Weather forecast for your location
2. Allow the app to use your location