Well above average conditions will continue through the end of the week. Some cooling is expected through the weekend into early next week, but temperatures will remain above average. Marine layer low clouds and fog will be largely absent from the coast this week, potentially returning by late this weekend.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, NEW AVIATION DISCUSSION BELOW,
Temperatures at 11 AM were running 5 to 10 degrees cooler than yesterday for the coast and parts of the western valleys. The mountains and deserts were running 5 to 10 degrees warmer than yesterday. A daily and monthly high and low temperature records were broken yesterday with more expected to be broken each day through Friday. A climate section can be found below with more information. Widespread moderate to locally major HeatRisk is expected through Friday for most locations and Saturday in the low desert. Reduce outdoor activities if possible between 10 AM and 5 PM, seek shade, and stay hydrated.
The high pressure aloft will peak in strength Friday with high temperatures 20 to 30 degrees above average for this time of year. Overnight lows will also be elevated, which will limit overnight relief from the heat for most locations. Through Friday Widespread temperatures in the 90s to low 100s expected for the inland valleys, with highs in the mid-80s to low 90s for coastal areas away from the immediate coast and the lower elevations of the mountains. In the low deserts, highs will likely exceed 105 degrees in most locations through Saturday. Chances for exceeding 110 degrees on Friday are 70 percent for Indio, 30 percent for Palm Springs, and 20 percent for Borrego Springs. In the High Desert, temperatures will be in the mid- 90s.
Weakening high pressure aloft and strengthening onshore flow will bring 4 to 8 degrees of cooling Saturday. That will be most noticeable for locations west of the mountains, but even the deserts will cool 3 to 5 degrees. A weak low pressure system aloft will move east through Southern California into the Great Basin sometime Sunday or Monday. That will bring an uptick in westerly winds Saturday, which have the potential to turn weakly offshore by Sunday or Monday. Weak ridging aloft will return sometime next Tuesday or Wednesday, maintaining above average temperatures. Low clouds will remain absent from the coast through the work week. Patchy low clouds may return with the return of onshore flow over the weekend.
190000z, Mostly clear skies and VFR conditions through Thursday afternoon. Patchy fog over coastal waters tonight into Thursday, but unlikely to impact coastal airports.
No hazardous marine conditions are expected throughSunday.
Ca, Heat Advisory until 8 PM PDT Friday for Riverside County Mountains-San Bernardino County Mountains-San Diego County Mountains.
PZ, None.
