The highest day temperature in May 2026 was 94°F. The lowest night temperature was 26°F. The average values for day and night temperatures during May were 70.0°F и 47.4°F respectivly.

Most of the days in May are sunny but you can also expect cloudy and gloomy days.

Precipitation total in May for Great Falls is 1.3 in. It makes may the most rainy month of the year.

The average wind speed in May is 8.1 mph. This value is relatively stable throughout the year.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Great Falls in May is 9.1 hours.