Pasadena’s prolonged heat wave is expected to continue through Thursday with temperatures nearing 100 degrees before a dramatic cooling trend lowers daytime highs into the 70s by Sunday and brings a chance of showers early next week, according to the National Weather Service.
Forecasters expect sunny and hot conditions Wednesday, with a high near 99 degrees. Light winds will become southwesterly at about 5 mph during the afternoon before diminishing in the evening. Overnight temperatures are expected to fall to about 68 degrees under clear skies.
The National Weather Service said a strong area of high pressure will maintain dangerous heat across the region through at least Thursday. Pasadena is forecast to reach a high of 98 degrees Thursday, with mostly unchanged conditions and light afternoon southwest winds.
Relief from the heat is expected to begin Friday as temperatures trend downward. The forecast calls for a high near 93 degrees under sunny skies.
The cooling trend becomes more pronounced over the weekend. Patchy fog is possible Friday night before partly sunny skies and a high near 83 degrees on Saturday. Temperatures are then expected to fall to about 76 degrees Sunday.
National Weather Service forecasters said a developing weather system along the West Coast, combined with moisture associated with the remnants of Hurricane Rachel, will bring cooler temperatures and a chance of precipitation to the area.
Pasadena’s first chance of showers arrives Sunday, mainly after 11:00 a.m. Shower chances continue Sunday night, Monday and Monday night. Monday’s high temperature is expected to reach only about 71 degrees.
The National Weather Service forecast discussion indicates Los Angeles County could receive measurable rainfall if the system develops as projected, with the potential for the greatest amounts in eastern portions of the county. Specific rainfall amounts for Pasadena were not provided.
A slight chance of showers remains in the forecast Tuesday, when temperatures are expected to recover slightly, with a high near 74 degrees.
The forecast marks a significant shift for Pasadena, transitioning from near-triple-digit heat through Thursday to temperatures below normal and the possibility of rain by the beginning of next week.
Here is the Pasadena forecast from the National Weather Service as of 2:39 a.m. Wednesday:
Today: Sunny and hot, with a high near 99. Calm wind becoming southwest around 5 mph in the afternoon.
Tonight: Clear, with a low around 68. West southwest wind around 5 mph becoming calm in the evening.
Thursday: Sunny and hot, with a high near 98. Calm wind becoming southwest around 5 mph in the afternoon.
Thursday Night: Clear, with a low around 67. Southwest wind around 5 mph becoming calm in the evening.
Friday: Sunny, with a high near 93. Calm wind becoming south southwest around 5 mph in the afternoon.
Friday Night: Patchy fog after 11:00 p.m. Otherwise, mostly cloudy, with a low around 63.
Saturday: Patchy fog before 11:00 a.m. Otherwise, partly sunny, with a high near 83.
Saturday Night: Mostly cloudy, with a low around 59.
Sunday: A chance of showers, mainly after 11:00 a.m. Partly sunny, with a high near 76.
Sunday Night: A chance of showers. Mostly cloudy, with a low around 54.
Columbus Day: A chance of showers. Partly sunny, with a high near 71.
Monday Night: A chance of showers. Mostly cloudy, with a low around 52.
Tuesday: A slight chance of showers. Mostly sunny, with a high near 74.
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