May weather forecastBoulder, CO
May
Weather in May
May denotes the onset of more agreeable conditions in Boulder, as spring starts to give way to the impending summer. Overall, it is characterised by the longest daylight span of the year, warmer temperatures and heightened humidity levels. By this time, rain peaks to its yearly high, reaching an amount of about 2.48" (63mm). The advent of June will denote increased temperatures and the official beginning of the summer season. As such, May is a month of pleasant and diverse climatic shifts.Temperature
With the onset of May, Boulder's average high-temperature sees a modest rise, moving from April's cool 52.3°F (11.3°C) to a refreshing 61°F (16.1°C). Significant dips from daytime highs mark the May nights, with a consistent average temperature of 38.7°F (3.7°C).Humidity
In May, the average relative humidity is 58%.Rainfall
The month with the most rainfall is May, when the rain falls for 17.5 days and typically aggregates up to 2.48" (63mm) of precipitation.Snowfall
January through May, October through December are months with snowfall. May is the last month it regularly snows. During 1.7 snowfall days, in May, Boulder aggregates 1.65" (42mm) of snow. In Boulder, during the entire year, snow falls for 44.8 days and aggregates up to 37.01" (940mm) of snow.Daylight
In May, the average length of the day is 14h and 25min.On the first day of the month, sunrise is at 5:59 am and sunset at 7:56 pm. On the last day of May, sunrise is at 5:34 am and sunset at 8:23 pm MDT.
Sunshine
In May, the average sunshine is 10.7h.UV index
The average daily maximum UV index in May is 4. A UV Index reading of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for the average person.Note: An average maximum UV index of 4 in May leads to these recommendations:
Guard yourself - An obligation to protect skin and eyes from harm exists. Minimize direct exposure to the Sun during midday when its radiation is at its peak. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days. Consider carefully! The reflective quality of snow can almost double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in May
Boulder, CO
- Average high temperature in May: 61°F
The warmest month (with the highest average high temperature) is July (80.4°F).
The month with the lowest average high temperature is December (35.2°F).
- Average low temperature in May: 38.7°F
The month with the highest average low temperature is July (55.2°F).
The coldest month (with the lowest average low temperature) is February (18°F).
Average pressure in May
Boulder, CO
- Average pressure in May: 29.92"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The months with the lowest atmospheric pressure are April, May and June (29.92"Hg).
Average wind speed in May
Boulder, CO
- Average wind speed in May: 5.7mph
The windiest month (with the highest average wind speed) is January (7.3mph).
The calmest months (with the lowest average wind speed) are May, July, August and September (5.7mph).
Average humidity in May
Boulder, CO
- Average humidity in May: 58%
The month with the highest relative humidity is February (70%).
The months with the lowest relative humidity are June, August and September (45%).
Average rainfall in May
Boulder, CO
- Average rainfall in May: 2.48"
The wettest month (with the highest rainfall) is May (2.48").
The driest month (with the least rainfall) is January (0.39").
Average rainfall days in May
Boulder, CO
- Average rainfall days in May: 17.5 days
The month with the highest number of rainy days is July (17.8 days).
The month with the least rainy days is November (3.3 days).
Average snowfall in May
Boulder, CO
- Average snowfall in May: 1.65"
The month with the highest snowfall is April (7.76").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in May
Boulder, CO
- Average snowfall days in May: 1.7 days
The month with the highest number of snowfall days is February (10.3 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in May /
Average sunshine in May
Boulder, CO
- Average daylight in May: 14h and 24min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in May: 10h and 42min
The months with the most sunshine are June and July (Average sunshine: 11h and 42min).
The month with the least sunshine is February (Average sunshine: 6h and 36min).
Average sunshine days in May
Boulder, CO
- Average sunshine days in May: 10.9 days
The month with the most sunshine days is January (22.2 days).
The month with the least sunshine days is July (9.9 days).
Average UV index in May
Boulder, CO
- Average UV index in May: 4
The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in May
Boulder, CO
- Average cloud cover in May: 28
The months with the most cloud cover are April and May (Cloud cover 28).
The month with the least cloud cover is September (Cloud cover 16).
Average visibility in May
Boulder, CO
- 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).
