The mercury will soar into the triple digits across most of the Inland Empire later this week, prompting the National Weather Service to issue an Extreme Heat Watch for the region.
“An upper level high pressure system currently just east of the Four Corners will slowly migrate west,” the NWS said in a statement Monday. “High temperatures will warm a few degrees each day. The chances of the Inland Empire reaching or exceeding 105 degrees (by) Thursday are 70 to 80%.”
The Extreme Heat Watch begins at 10 a.m. Thursday and concludes to 8 p.m. Friday. However, temps are expected to remain elevated through the weekend.
“Drink plenty of fluids, stay in air-conditioned rooms and stay out of the sun,” the NWS stated. “Heat-related illnesses increase significantly during extreme heat events.”
The ridge of high pressure now near the Four Corners will back into southeast California, grinding into a trough of low pressure that will create instability in the mountains and deserts, where scattered thunderstorms are possible toward the end of the week as the low draws energy from Baja California in Mexico, according to forecasters.
High temperatures in the Riverside metropolitan area Monday and Tuesday will hover in the mid 90s, increasing to the upper 90s Wednesday and topping out at or just above 100 on Thursday, Friday and possibly Saturday. Lows throughout the week will settle in the upper 60s, the Weather Service said.
In the Coachella Valley, highs Monday and Tuesday will peak around 108, but Wednesday, the daytime mercury will edge above 110, while Thursday to Saturday, temps will approach 115 in many desert locations. The mercury may be slightly checked by monsoonal activity and thunderstorm development, forecasters said. Lows throughout the week will generally stay in the mid to upper 80s.
In the Temecula Valley, the temperature band will be moderated by coastal influences, with highs in the upper 80s Monday and Tuesday, followed by low to mid 90s for the balance of the week. Lows will mostly hover in the low to mid 60s, meteorologists said.