May weather forecast and climate
St. Louis, MO

A beautiful twilight view of the Gateway Arch in St. Louis, Missouri, with a distant view of the city buildings mirrored in the waterfront
A beautiful twilight view of the Gateway Arch in St. Louis, Missouri, with a distant view of the city buildings mirrored in the waterfront
The last month of the spring, May, is a moderately hot month in St. Louis, with average temperature varying between 57.2°F (14°C) and 76.3°F (24.6°C).

Temperature

In May, the average high-temperature in St. Louis slightly increases, from a comfortable 67.5°F (19.7°C) in April, to a moderately hot 76.3°F (24.6°C). The average low-temperature, in St. Louis, is 57.2°F (14°C).

Humidity

In St. Louis, Missouri, the average relative humidity is 66.5%.

Rainfall

The month with the most rainfall in St. Louis is May when the rain falls for 11.9 days and typically aggregates up to 4.72" (119.9mm) of precipitation.

Snowfall

In St. Louis snow does not fall in May through October.

Daylight

In St. Louis, the average length of the day is 14.3h.

Sunshine

In St. Louis, the average sunshine is 8.6h.

UV index

In St. Louis, the average daily maximum UV index in May is 8. A UV Index estimate of 8 to 10 represents a very high threat to health from the exposure to the Sun's UV rays for the average person.
Note: In May, the average maximum UV index of 8 translate into the following recommendations:
Take extra precautions. Fair-skinned individuals may get burned in less than 10 minutes. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.

What is the temperature in May in St. Louis?

The average high-temperature, in May, in St. Louis, Missouri, is 76.3°F (24.6°C), while the average low-temperature is 57.2°F (14°C).

What is the average humidity in May in St. Louis?

The average relative humidity in May in St. Louis is 66.5%.

How much does it rain in St. Louis in May?

In May, in St. Louis, the rain falls for 11.9 days. Throughout May, 4.72" (119.9mm) of precipitation is accumulated.

What is the wettest month in St. Louis?

May is the month with the most rainfall in St. Louis. Rain falls for 11.9 days and accumulates 4.72" (119.9mm) of precipitation.

Does it snow in St. Louis in May?

In May, it doesn't snow. April is the latest month when it typically snows.

When it does not snow in St. Louis?

In St. Louis, Missouri, snow does not fall in May through October.

What is the average length of the day in May in St. Louis?

In May, the average length of the day is 14.3h.

How many hours of sunshine does St. Louis have in May?

In St. Louis, the average sunshine in May is 8.6h.

What is the UV index reading in May in St. Louis?

In St. Louis, Missouri, the average daily maximum UV index in May is 8. A UV Index estimate of 8 to 10 represents a very high health vulnerability from the exposure to the Sun's UV rays.
Average temperature in May - St. Louis, MO
  • Average high temperature in May: 24.6°C

The warmest month (with the highest average high temperature) is July (31.7°C).
The month with the lowest average high temperature is January (4.4°C).

  • Average low temperature in May: 14°C

The month with the highest average low temperature is July (21.7°C).
The coldest month (with the lowest average low temperature) is January (-4.6°C).

Average humidity in May - St. Louis, MO
  • Average humidity in May: 66.5%

The month with the highest relative humidity is December (75.8%).
The month with the lowest relative humidity is April (63.5%).

Average rainfall in May - St. Louis, MO
  • Average rainfall in May: 119.9mm

The wettest month (with the highest rainfall) is May (119.9mm).
The driest month (with the least rainfall) is February (56.9mm).

Average rainfall days in May - St. Louis, MO
  • Average rainfall days in May: 11.9 days

The month with the highest number of rainy days is May (11.9 days).
The month with the least rainy days is September (7.4 days).

Average snowfall in May - St. Louis, MO
  • Average snowfall in May: 0mm

The month with the highest snowfall is January (142.2mm).
Months with the least snowfall are May, June, July, August, September and October (0mm).

Average snowfall days in May - St. Louis, MO
  • Average snowfall days in May: 0 days

The month with the highest number of snowfall days is January (4.7 days).
Months with the least snowfall days are May, June, July, August, September and October (0 days).

Average daylight in May / Average sunshine in May - St. Louis, MO
  • Average daylight in May: 14.3h

The month with the longest days is June (Average daylight: 14.8h).
The month with the shortest days is December (Average daylight: 9.5h).

  • Average sunshine in May: 8.6h

The month with the most sunshine is July (Average sunshine: 10h).
The month with the least sunshine is December (Average sunshine: 4.2h).

Average UV index in May - St. Louis, MO
  • Average UV index in May: 8

Months with the highest UV index are June, July and August (UV index 9).
Months with the lowest UV index are January and December (UV index 2).