Riverside weather in May
In May, Riverside has daytime highs averaging 26 °C, nights around 13 °C, with 2.7 wet days. Figures are 1991–2020 climate normals.
- 26.0°C Average high
- 12.5°C Average low
- 2.7days Wet days
- 14mm 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 | 25.4 °C | 11.9 °C | 13 % |
| 11–20 May | 26.3 °C | 12.6 °C | 7 % |
| 21–31 May | 26.2 °C | 12.9 °C | 7 % |
- Rain is most likely over days 1–10 of May (13 % of days) and least likely over days 21–31 (7 %).
What to expect
| Measure | Typical May | Share of the month |
|---|---|---|
| Days above 25 °C | 18 of 31 | 57 % |
| Days above 30 °C | 6.8 of 31 | 22 % |
| Days below 0 °C | 0 of 31 | 0 % |
| Days with more than 1 mm rain | 2.7 of 31 | 9 % |
Conditions in May
| Measure | Average |
|---|---|
| Mean temperature | 18 °C |
| Record high (1991–2020) | 39 °C |
| Record low (1991–2020) | 5.2 °C |
| Relative humidity | 62 % |
| Wind speed | 13 km/h |
| Cloud cover | 37 % |
Where Riverside ranks in May
| Ranking | Position | Value |
|---|---|---|
| Places with the best weather in North America in May | 23rd of 50 | 92/100 |
| The driest places in North America in May | 45th of 50 | 14 mm |
May compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| March | 20.7 °C | 64 mm | 50 % |
| April | 23.4 °C | 31 mm | 42 % |
| May | 26.0 °C | 14 mm | 37 % |
| June | 29.9 °C | 3 mm | 21 % |
| July | 33.0 °C | 2 mm | 18 % |
See all twelve months for Riverside
- May is the 6th warmest month here.
- It is the 5th driest month of the year.
- It ranks 7th for least cloud cover.
- Days last about 14 hours from sunrise to sunset.
- It rains on 2.7 of 31 days — 9 % of the month.
- Nights are about 14 °C cooler than the middle of the day.
- The hottest May day on record since 1991 reached 39 °C, 13 °C above the usual daytime high.
QuestionsMay in Riverside, answered
How warm is Riverside in May?
Daily highs average 26 °C and nights fall to about 13 °C, a spread of 14 °C between afternoon and dawn. That makes May the 6th warmest month of the year here.
Does it rain much in Riverside in May?
May averages 14 mm of rain, spread over about 3 of the 31 days — 9 % of the month. Cloud cover averages 37 % of the sky.
How long are the days in May?
Riverside 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.