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Temperatures are expected to jump significantly across Southern California between Tuesday and Thursday this week, which marks the first full week of summer.<\/p>\n
The National Weather Service has issued an extreme heat watch<\/a> for those days, forecasting 90-degree temperatures in downtown Los Angeles and the L.A. metro area \u2014 a marked increase from the 75-degree high on Saturday, the last day of spring.<\/p>\n Highs are expected to reach the mid-90s in the San Gabriel Valley and the San Fernando Valley, and possibly climb to 100 degrees or higher in the Antelope Valley and the Cuyama Valley in Santa Barbara County, said Weather Service spokesperson Carol Ciliberti. <\/p>\n Wednesday will probably be the hottest day, she said.<\/p>\n The heat wave stems from \u201ca really strong ridge of high pressure,\u201d Ciliberti said. \u201cIt\u2019s centered over Arizona and New Mexico and their southern border with Mexico, but it expands to the west over Southern California.\u201d<\/p>\n She said the increased temperatures bring a higher risk of heat-related illnesses, especially for the young, the elderly and those without air conditioning.<\/p>\n \u201cDo not take your dogs hiking \u2014 please,\u201d she said.<\/p>\n The upcoming heat wave should bring a respite from \u201cJune Gloom\u201d\u2014 the ocean clouds and fog that are typical this time of year \u2014 although the familiar marine-layer grayness may soon return. In March, prolonged high temperatures shattered dozens of records<\/a> in Southern California. <\/p>\n Next week\u2019s expected heat wave brings an elevated risk of fire, the Weather Service noted in an X post<\/a>, \u201cwith drying fuels & tall fire plume potential over the valleys and mountains.\u201d <\/p>\n On Saturday, officials extended a health advisory because of particle pollution from a massive warehouse fire in Boyle Heights<\/a>. The advisory is in effect until 12:30 p.m. Sunday.<\/p>\n