An extended period of hot weather is expected across much of Southwestern California this week, due to a strong upper level high pressure system strengthening over the area from Monday through Thursday.

The system is expected to bring a prolonged period of hot weather, with temperatures in the valleys in the triple digits, ranging from 98 to 108 degrees for the next several days.

The warmest temperatures are expected on Tuesday and Wednesday. Forecasters from the National Weather Service are saying this will be the warmest weather of the summer so far.

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Inland portions of the coastal plan are expected to soar well into the 90s and offshore winds could bring 90 degree temperatures to some of the beaches along the Central Coast.

During the peak of the heat wave on Tuesday and Wednesday, the following temperatures can be expected:

• Valleys 98-108 degrees
• Lower Mountains 96-107 degrees
• Antelope Valley 102-110 degrees

The combination of very hot temperatures and moderate humidity has prompted an “excessive heat watch” to be issued for the lower mountains and some valley locations. In addition, the prolonged nature of the heat wave, along with increasingly warm nights through mid-week will prevent sufficient cooling in non-air conditioned places, making for potentially dangerous conditions.

Residents should prepare for the long stretch of hot weather. If you have to be outside for an extended period of time, stay in the shade as much as possible and drink plenty of water. Limit any outdoor strenuous activities to the hours of the early morning or after sundown. Wear light-colored and loose-fitting clothing.

Most importantly, never leave children, the elderly or pets in enclosed automobiles, even for a short period of time, even with the windows partially open, as temperatures can still quickly rise to life-threatening levels.