St. Louis weather in May
In May, St. Louis has daytime highs averaging 25 °C, nights around 14 °C, with 13 wet days. Figures are 1991–2020 climate normals.
- 24.8°C Average high
- 14.5°C Average low
- 13days Wet days
- 129mm Rainfall
- 14h Daylight
Daily temperatures through May
How May develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 May | 23.2 °C | 12.7 °C | 40 % |
| 11–20 May | 24.3 °C | 13.9 °C | 44 % |
| 21–31 May | 26.5 °C | 16.4 °C | 40 % |
- Average highs rise from 23.2 °C early in May to 26.5 °C by the end of it.
What to expect
| Measure | Typical May | Share of the month |
|---|---|---|
| Days above 25 °C | 16 of 31 | 52 % |
| Days above 30 °C | 3.1 of 31 | 10 % |
| Days below 0 °C | 0 of 31 | 0 % |
| Days with more than 1 mm rain | 13 of 31 | 42 % |
Conditions in May
| Measure | Average |
|---|---|
| Mean temperature | 19 °C |
| Record high (1991–2020) | 36 °C |
| Record low (1991–2020) | 2.3 °C |
| Relative humidity | 69 % |
| Wind speed | 18 km/h |
| Cloud cover | 59 % |
May compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| March | 13.7 °C | 99 mm | 62 % |
| April | 19.8 °C | 117 mm | 58 % |
| May | 24.8 °C | 129 mm | 59 % |
| June | 29.4 °C | 109 mm | 53 % |
| July | 31.3 °C | 94 mm | 48 % |
See all twelve months for St. Louis
- May is the 5th warmest month here.
- It is the 12th driest month of the year.
- It ranks 8th for least cloud cover.
- Days last about 14 hours from sunrise to sunset.
- It rains on 13 of 31 days — 42 % of the month.
- Nights are about 10 °C cooler than the middle of the day.
- The hottest May day on record since 1991 reached 36 °C, 11 °C above the usual daytime high.
QuestionsMay in St. Louis, answered
How warm is St. Louis in May?
Daily highs average 25 °C and nights fall to about 14 °C, a spread of 10 °C between afternoon and dawn. That makes May the 5th warmest month of the year here.
Does it rain much in St. Louis in May?
May averages 129 mm of rain, spread over about 13 of the 31 days — 42 % of the month. Cloud cover averages 59 % of the sky.
How long are the days in May?
St. Louis averages 14 hours between sunrise and sunset in May. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.