May weather forecast
Yellowstone National Park, WY

May in Yellowstone National Park brings warmer weather and longer days. The maximum temperature approaches pleasant highs of 51.9°F (11.1°C), making outdoor exploration more enjoyable. Rainfall is at its peak, renewing the park's plentiful flora and enriching the vibrancy of the landscape. Wildlife enthusiasts can witness animals caring for their offspring. Rivers brim with melting snow, attracting waterfowlers eager to return for the season.

Temperature

May's arrival brings a modest temperature shift, moving from a frosty 43.3°F (6.3°C) in April to a fresh 52°F (11.1°C). Yellowstone National Park reports a significant contrast between daytime and nighttime temperatures, with an average low of 28°F (-2.2°C) in May.

Rainfall

May is the month with the most rainfall. Rain falls for 11.5 days and accumulates 2.48" (63mm) of precipitation.

Snowfall

January through June, September through December are months with snowfall. In Yellowstone National Park, in May, snow falls for 4.4 days, with typically accumulated 8.11" (206mm) of snow. Throughout the year, there are 91.4 snowfall days, and 193.7" (4920mm) of snow is accumulated.

Daylight

In May, the average length of the day is 14h and 49min.
On the first day of May, sunrise is at 6:11 am and sunset at 8:27 pm. On the last day of the month, sunrise is at 5:40 am and sunset at 8:59 pm MDT.

Sunshine

In Yellowstone National Park, the average sunshine in May is 9h.

UV index

In May, the average daily maximum UV index is 8. A UV Index value of 8 to 10 symbolizes a very high health hazard from exposure to the Sun's UV rays for ordinary individuals.
Note: The UV index of 8 during May translates into the following guidance:
Swift harm can befall unprotected skin and eyes. Prioritize safety. Stay in the shade and limit direct Sun exposure from 10 a.m. to 4 p.m., a time when UV radiation is particularly strong. Remember, however, that shade structures may not provide complete protection. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection. Be on the lookout! Nearly twofold UV radiation from the Sun can be reflected by snow.