Usually the weather in Rancho Cucamonga during May is 17. Highs are expected to be 26 with low average temperatures being 12 celsius. The table below includes more detail:
| Month | Degrees Celsius |
|---|---|
| Temperature | 17 |
| High Temperature | 26 |
| Low Temperature | 12 |
| Sunshine Per Day | 10 |
Useful Links: Rancho Cucamonga Weather: Average Weather & Yearly Climate