A high pressure system continues to build over the region Sunday, bringing triple-digit temperatures to most of the Inland Empire through the Labor Day weekend and prompting the National Weather Service to issue a heat advisory.
The advisory is in effect through 8 p.m. Monday, covering all of the valleys in Riverside and San Bernardino counties. Temperatures at higher elevations are forecast to be milder but still unseasonably warm.
“Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun,” an NWS statement advised. “Take extra precautions if you work or spend time outside. When possible, reschedule strenuous activities to early morning or evening.”
Temperatures on Sunday were expected to be up to 10 degrees above average, with highs forecast to reach 112 degrees in Palm Springs, 109 in Lake Elsinore, 105 in Riverside, 108 in Hemet and 91 in Idyllwild, according to the NWS.
Although a few degrees will be knocked off those temperatures by Monday, many places around the Inland Empire will still see the mercury surpass the century mark on Labor Day.
Overnight lows throughout the long weekend will be in the low 70s in the Riverside metropolitan area and in the 80s in the Coachella Valley, according to the NWS.
Meteorologists said a ridge of high pressure building over Central California will dominate the region, reducing relative humidity and creating bone-dry conditions.
“With the heat building in, combined with dry fuels and diurnal winds, a few hours of elevated fire weather conditions are possible for inland areas each afternoon this weekend and early next week,” the NWS stated.
The ridge will cede to lower pressure systems going into Tuesday, drawing moisture from the coasts and returning temperatures to more seasonable levels, forecasters said.