Widespread well above average temperatures expected into next week. High and low temperature records are expected to be tied or broken every day through the next week. Heat this week will peak Thursday and Friday, brief "cool down" for the weekend, before another increase next week which looks likely to peak mid-week. Widespread moderate HeatRisk for the valleys, inland coastal areas, and the lower deserts for Thursday and Friday of this week and for much of next week beginning on Monday, heat-related illnesses are likely for sensitive populations.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Widespread clear skies are being observed on satellite as of 12 PM today. Prevailing weak offshore flow will keep marine layer low clouds and fog from developing through Friday. North to northeast winds today will peak at 25 to 35 mph on the coastal slopes of the mountains. Weak onshore flow returns for the weekend into next week, but any low cloud or fog development looks patchy and confined to the immediate coast.
A ridge of high pressure will move east over the US West Coast for Thursday and Friday, which will bring high temperatures west of the mountains 20 to 25 degrees above average. Widespread moderate HeatRisk can be expected for the coast and valleys. The mountains and deserts will see highs 15 to 20 degrees above average. There will be limited overnight relief from the heat due to elevated overnight lows. Take extra precautions if working/recreating outside. Wear lightweight and loose fitting clothing. Try to limit strenuous activities to early morning or evening. Take action when you see symptoms of heat exhaustion and heat stroke. Many high temperatures records across much of area are likely to be tied or broken on Thursday and Friday. There will also be some record warm overnight temperatures on Thursday, mainly for the mountains and inland valleys, with more on Friday.
A weak low pressure system moving inland across the Pacific Northwest on Friday night will weaken high pressure aloft over southern California through Saturday with mid and high clouds spreading across the area for late Friday through late Saturday. This weak system will bring 3 to 5 degrees of cooling for the coast, valleys, and mountains with minimal change for the deserts. High pressure aloft will restrengthen Sunday and Monday, brining another uptick in temperatures. Temperatures look to peak sometime mid-week, with the hottest conditions expected in the low deserts. Areas of major HeatRisk are possible in the low deserts during the peak of the heat. Tuesday's NBM chances for high temperatures to exceed 85 at the coast are 70-80 percent; chances of exceeding 95 in San Diego valleys and inland Orange County are 60-75 percent; and in the Inland Empire chances of exceeding 95 are 90+ percent. For the low desert, chances of exceeding 105 degrees on Tuesday are 60-70 percent and closer to 80 percent on Wednesday. Record breaking high temperatures are expected through the forecast period.
111730z, VFR conditions expected through the TAF period. Slight chance (10-20%) of low clouds/FG at the immediate coastline Thursday morning. Otherwise, offshore flow will prevent any marine layer clouds from impacting the coastal basin.
No hazardous marine conditions are expected through Monday.
Long period southerly swell with heights of 2-3 ft and periods of 19-21 seconds will create elevated surf along south and southwest-facing beaches through Thursday night. Surf heights generally 3-6 feet with sets to 7 feet.
KW
Ca, Heat Advisory from 10 AM Thursday to 8 PM PDT Friday for Orange County Coastal Areas-Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire- San Diego County Coastal Areas-San Diego County Valleys.
PZ, None.
