The highest day temperature in May 2025 was 86°F. The lowest night temperature was 45°F. The average values for day and night temperatures during May were 71.2°F и 52.1°F respectivly.

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

Precipitation total in May for Siena is 2.2 in. It makes may one of the most rainy months of the year.

The average wind speed in May is 5.6 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 Siena in May is 9.9 hours.