Slow cooling was predicted to continue in San Diego County Thursday through Friday with gusty southwest to west winds for the mountains and deserts during the afternoons and evenings, the National Weather Service said.
Slow warming was likely to begin during the weekend with greater warming for next week as high pressure to the east strengthens and expands westward across California, forecasters said.
Coastal areas should warm around 5 degrees from the middle of this week and inland areas around 10 degrees.
Early next week could be the beginning of a long duration heat wave for inland areas, especially for the deserts, that could last a week or more, the NWS said.
The marine layer was expected to moderate the heat toward the coast.
Along the coast Thursday, it was expected to be mostly sunny with high temperatures from 68 to 73 degrees, the NWS said. The western valleys were expected to be mostly sunny with highs from 75 to 80 and near the foothills from 83 to 88. It should be sunny in the mountains with highs from 81 to 91. The deserts were expected to be sunny with highs from 105 to 110.
It will remain very dry for inland areas the next few days with lowest daytime humidity for the deserts onto the desert slopes of the mountains of 5% to 10%. The very low humidity combined with gusty sea breeze winds during the afternoon and evening were likely to result in near critical fire weather conditions during the afternoon and early evening each day through Friday, then elevated fire weather conditions for the weekend.
High pressure to the east was expected to strengthen and expand westward through next Wednesday. This could bring a warming trend through Tuesday, greater for inland areas, with not much change on Wednesday.
In general, high and low temperatures for inland areas for the middle of next week may be around 10 degrees higher than the middle of this week with coastal areas around 5 degrees higher.
Winds could approach 20 knots over portions of the outer coastal waters in the afternoons and evenings Thursday through Saturday. Otherwise, no hazardous marine weather was expected through Monday.