Wintry weather and frost in the valleys around Riverside early this morning may be possible again late tonight ahead of a noticeable warmup later this week.
As of about 9 p.m. Tuesday, temperatures had dropped into the 40s in many areas west of the mountains and into the 30s in a few spots, according to the National Weather Service. A frost advisory for the valleys in Riverside County is scheduled to expire at 8 a.m. today.
The advisory did not extend to the Coachella Valley or the San Gorgonio Pass, but forecasters said frost could be possible in wind-sheltered locales.
Forecasters said a dry, cold air mass would result in areas of frost as temperatures fall into the mid-20s to low 30s in wind-sheltered valleys. Overnight low temperatures were forecast to be 24 degrees in Anza, 28 in Temecula, 31 in Hemet, 33 in Thermal and Lake Elsinore, 35 in Riverside and 42 in Palm Springs.
Tonight will be slightly less chilly in most areas, but patchy frost will be likely in the coldest valleys, according to the weather service. Forecasters urged residents to cover sensitive outdoor vegetation and bring pets inside.
Temperatures are expected to be noticeably warmer Thursday and Friday, but light rain may be possible over the weekend, according to the NWS.
In the valleys, high temperatures of 56 to 61 degrees are expected to jump to around 72 degrees on Friday. In the mountains, 43- to 48-degree highs will rise into the low to mid-60s, and highs in the upper 50s to low 60s along the San Gorgonio Pass will increase to 65 to 70 degrees Friday.
A slight warmup is expected this week in the Coachella Valley. High temperatures of 62 to 67 degrees today are expected to inch up to around 69 degrees by the end of the work week.