An unseasonable hot spell will continue Thursday in San Diego County, but cooling will arrive throughout the region on Friday, according to the National Weather Service.
The high pressure that has brought blazing temperatures all week will weaken Thursday, then a trough of low pressure will move in from the coast on Friday, forecasters said.
High temperatures Thursday are forecast to reach 80 degrees near the coast, 89 inland, 94 in the western valleys, 93 in the mountains and 108 in the deserts.
Highs in the western valleys will drop to the mid-70s to low-80s on Friday, while temperatures in coastal areas will max out in the low- to high- 70s, according to the NWS.
However, the relief will be short-lived because another ridge of high pressure is set to arrive early next week and cause temperatures to heat up again, forecasters said.
Temperature records for June 10 were set in El Cajon and at the Oceanside harbor on Wednesday, while Chula Vista tied its previous high for the date.
The 99-degree high in El Cajon broke the previous record of 84 for that date, set in 1993, according to the NWS. Records date back to 1979.
A new high was also reached at Oceanside harbor, where an 80-degree temperature beat the previous best for the date, 76 in 1966. Records date back to 1910.
Chula Vista's 86-degree high tied its record for the date, set in 1979. Records date back to 1918.
