May weather forecastGrand Coulee, WA
May
Weather in May
The last month of the spring, May, is a comfortable month in Grand Coulee, Washington, with an average temperature fluctuating between 46°F (7.8°C) and 67.6°F (19.8°C).Temperature
The shift from April to May sees an increase in the average high-temperature, transitioning from a refreshing 57°F (13.9°C) to a comfortable 67.6°F (19.8°C). Despite considerable daily temperature swings, a steady low-temperature average of 46°F (7.8°C) is noted throughout May.Humidity
The average relative humidity in May is 52%.Rainfall
The months with the most rainfall are May and December, with an average 1.18" (30mm) of precipitation.Snowfall
In Grand Coulee, snow does not fall in May through August.Daylight
In May, the average length of the day is 15h and 12min.On the first day of the month, sunrise is at 5:36 am and sunset at 8:09 pm. On the last day of May, sunrise is at 5:00 am and sunset at 8:46 pm PDT.
Sunshine
In May, the average sunshine is 10.9h.UV index
In Grand Coulee, 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 average daily UV index of 5 in May transforms into the following instructions:
Heed the precautions - Protecting the skin and eyes from damage is compulsory. For health reasons, it's advisable to reduce direct sun exposure during peak hours around midday. Prioritize a wide-brim hat for comprehensive sun defense for your face, neck, eyes, and ears.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in May
Grand Coulee, WA
- Average high temperature in May: 67.6°F
The warmest month (with the highest average high temperature) is July (84.9°F).
The month with the lowest average high temperature is December (31.6°F).
- Average low temperature in May: 46°F
The month with the highest average low temperature is August (61.3°F).
The coldest month (with the lowest average low temperature) is December (21.4°F).
Average pressure in May
Grand Coulee, WA
- Average pressure in May: 29.94"Hg
The month with the highest atmospheric pressure is January (30.18"Hg).
The month with the lowest atmospheric pressure is August (29.91"Hg).
Average wind speed in May
Grand Coulee, WA
- Average wind speed in May: 6.3mph
The windiest month (with the highest average wind speed) is April (7mph).
The calmest month (with the lowest average wind speed) is January (4.9mph).
Average humidity in May
Grand Coulee, WA
- Average humidity in May: 52%
The month with the highest relative humidity is January (89%).
The month with the lowest relative humidity is August (36%).
Average rainfall in May
Grand Coulee, WA
- Average rainfall in May: 1.18"
The wettest months (with the highest rainfall) are May and December (1.18").
The driest months (with the least rainfall) are July and August (0.2").
Average rainfall days in May
Grand Coulee, WA
- Average rainfall days in May: 10.8 days
The month with the highest number of rainy days is March (12.1 days).
The month with the least rainy days is August (3.2 days).
Average snowfall in May
Grand Coulee, WA
- Average snowfall in May: 0"
The month with the highest snowfall is January (4.41").
The months with the least snowfall are May, June, July and August (0").
Average snowfall days in May
Grand Coulee, WA
- Average snowfall days in May: 0 days
The month with the highest number of snowfall days is December (10.5 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in May /
Average sunshine in May
Grand Coulee, WA
- Average daylight in May: 15h and 12min
The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in May: 10h and 54min
The month with the most sunshine is August (Average sunshine: 12h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).
Average sunshine days in May
Grand Coulee, WA
- Average sunshine days in May: 18 days
The month with the most sunshine days is August (25.8 days).
The month with the least sunshine days is March (14.7 days).
Average UV index in May
Grand Coulee, WA
- Average UV index in May: 5
The month with the highest UV index is July (UV index 7).
The month with the lowest UV index is November (UV index 1).
Average cloud cover in May
Grand Coulee, WA
- Average cloud cover in May: 28
The month with the most cloud cover is January (Cloud cover 55).
The months with the least cloud cover are July and August (Cloud cover 12).
Average visibility in May
Grand Coulee, WA
- Average visibility in May: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and December (4mi).
