Orange County is getting a breath of cool, moist air from the Pacific, bringing morning fog and cloudy days. The pattern — a normal one this time of year — could begin to shift by week’s end, with slightly higher temperatures and partly cloudy skies.

The credit, or the blame, should go to two masses of air that are working together. A system of higher pressure air over the ocean is being pulled inland by low pressure air over the mountains and deserts of the western United States, said National Weather Service forecaster Stan Wasowski.

“This time of year, the ocean has a fairly cool surface, about 62 degrees or so,” Wasowski said. “The air blows across the land; the clouds hanging around cool things down.”

The situation could reverse itself as early as Friday, Wasowski said, with higher pressure air inland pushing toward low pressure air off the coast. But while that could bump temperatures up into the 70s, it almost certainly won’t mean a return to hot weather.

A weather system to the southwest could bring rain on the weekend, although just how that system will move is difficult to predict, said National Weather Service forecaster Brandt Maxwell.

Expect partly cloudy skies Thursday, with patchy fog in the morning and evening, highs from the mid 60s to low 70s and light winds. Inland temperatures could rise to the high 70s Friday and Saturday. Add a slight chance of rain over the weekend; by Tuesday, we could be back to mostly sunny skies.

(Photo by Bruce Chambers)