By CBSLA Staff

LOS ANGELES (CBSLA) — What started as an excessive heat watch has been upgraded to an excessive heat warning beginning Friday at 11 a.m. and lasting through Monday at 9 p.m.

“Extreme heat will significantly increase the potential for heat-related illnesses, particularly for those working or participating in outdoor activities,” The National Weather Service said.

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The areas affected by the warning include Inland Empire which is expected to reach 100 to 110 degrees, Inland Orange County reaching 96 to 103 degrees, the high deserts set to reach between 102 and 112 degrees and the low deserts reaching 114 to 120 degrees.

The mountain areas below 5,000 feet are also included in the warning and are presumed to reach 92 to 102 degrees as well as the Ventura County coast and valleys which could get up to 102 degrees.

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The Los Angeles County coast, including Downtown, Hollywood, Beverly Hills and Long Beach are under a heat advisory that will also begin at 11 a.m. Friday but end by 9 p.m. Sunday.

Inland temperatures will be in the mid-90s, and overnight low temperatures away from the coast will only drop into the low 70s.

CBSLA meteorologist Amber Lee predicts the weather will feel a little more tropical over the next couple of days with muggy and humid conditions as Tropical Storm Elida increases moisture and instability to the Southland.

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There is a slight chance of showers Thursday morning.