Temperatures rose Tuesday across much of Southern California, part of a warming trend that will see the potential for triple-digit heat in some areas by mid-week and above-normal temperatures into at least Thursday.

Tuesday’s temperatures mirrored Monday’s, but the hottest days are expected to be today and Thursday, peaking today.

“The valleys will see max temps from 95 to 103 degrees, 15 to 20 degrees above normal,” according to the National Weather Service. “Warmer than normal highs and lows will combine to bring moderately dangerous heat conditions to the valleys and lower mountain elevations.”

Forecasters urged people planning outdoor activities today and Thursday to “take precautions to avoid heat-related dangers.”

A heat advisory is in effect at in the Santa Monica Mountains Recreational Area, Calabasas, Agoura Hills and the San Fernando Valley until 9 p.m. Thursday.

A separate heat advisory will be in place from 11 a.m. today until 9 p.m. Thursday for the Santa Clarita Valley, San Gabriel Valley and Los Angeles County coastal area stretching to downtown Los Angeles.

All the affected areas could see triple-digit heat, forecasters warned.

“There is a high risk for heat illness for sensitive populations including the very young, the very old, those without air conditioning, and those active outdoors,” according to the NWS.

A cooling trend is expected to begin Friday, and continue into the Memorial Day weekend, with the most significant drop occurring Saturday, returning temperatures to “a few degrees either side of normal,” followed by a few degrees of warming on Sunday.

Meanwhile, in the Riverside and San Bernardino County valleys, temperatures will rise today to 97 and Thursday to 95 with slight winds. The winds will die down today and Thursday.

By Friday, temperatures are expected to drop to the high 80s. By Saturday, temperatures will be around 80.

The mountains will be warm and windy with highs between 79 and 87.