Climate averages 1991–2020
Rancho Cucamonga weather
in May.
A warm, fairly dry month: the 6th warmest and the 5th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
May is a warm month in Rancho Cucamonga: daytime highs average 24.8°C and nights cool to about 12.2°C. By daytime temperature it is the 6th warmest of the 12 months.
Expect about 15 mm of rain on roughly 3 days, which makes May a fairly dry month (the 5th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 55 min on an average May day.
The nearest other city in this atlas is Ontario (7 km away). In May its highs average 24.6°C, about as warm as Rancho Cucamonga, with 11 mm of rain.
Among the 498 cities listed in the United States, Rancho Cucamonga ranks joint 206th of 498 for the warmest May highs and joint 79th of 498 for the driest May (rainfall, lowest first). The mean May high of those 498 cities is 23.8°C; Rancho Cucamonga is 1.1°C warmer than that mean.
From May to June, average highs rise by 4.0°C to 28.9°C, and monthly rainfall falls from 15 mm to 3.4 mm.
The annual picture
May in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Rancho Cucamonga climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 17.2°C5.6°C | 5.6°C | 96 | 6.6 | 10.210 h |
| February | 17.5°C6.1°C | 6.1°C | 111 | 7.4 | 10.911 h |
| March | 19.5°C7.7°C | 7.7°C | 68 | 6.8 | 12.012 h |
| April | 22.0°C9.4°C | 9.4°C | 32 | 4.6 | 13.013 h |
| May, selected | 24.8°C12.2°C | 12.2°C | 15 | 2.6 | 13.914 h |
| June | 28.9°C15.3°C | 15.3°C | 3.4 | 0.5 | 14.414 h |
| July | 32.3°C18.7°C | 18.7°C | 2.2 | 0.5 | 14.214 h |
| August | 33.3°C19.2°C | 19.2°C | 1.1 | 0.3 | 13.413 h |
| September | 31.4°C17.4°C | 17.4°C | 5.5 | 1.2 | 12.412 h |
| October | 26.4°C13.2°C | 13.2°C | 22 | 3.1 | 11.411 h |
| November | 21.3°C8.8°C | 8.8°C | 30 | 3.5 | 10.410 h |
| December | 16.9°C5.4°C | 5.4°C | 67 | 5.8 | 9.910 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
May in nearby cities
- Ontario in MayUnited States · 7 kmHigh 24.6°C · Low 12.4°C · 11 mm rain
- Chino in MayUnited States · 14 kmHigh 24.0°C · Low 12.5°C · 11 mm rain
- Fontana in MayUnited States · 15 kmHigh 24.8°C · Low 11.7°C · 15 mm rain
- Pomona in MayUnited States · 16 kmHigh 24.1°C · Low 12.1°C · 11 mm rain
- Chino Hills in MayUnited States · 20 kmHigh 23.5°C · Low 12.3°C · 11 mm rain
- Riverside in MayUnited States · 25 kmHigh 25.2°C · Low 12.3°C · 15 mm rain
- Corona in MayUnited States · 26 kmHigh 25.1°C · Low 13.1°C · 15 mm rain
- San Bernardino in MayUnited States · 28 kmHigh 25.2°C · Low 12.2°C · 13 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Rancho Cucamonga) is explained once on the Rancho Cucamonga year overview and on the Sources, method and limits page.
Riverside, Fontana and Corona lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.