Thunderstorm clouds
Thunderstorm clouds form over the mountains. Photo by Chris Stone

Sunny skies were forecast across San Diego County Sunday, with hot inland weather, where temperatures in the deserts may exceed 100 degrees, the National Weather Service said.

Monsoon moisture was moving back into Southern California from the southeast, and isolated showers or thunderstorms could develop over the mountains Sunday afternoon, forecasters said.

Increasing moisture and clouds Monday and Tuesday could temper the heat, but bring better chances for more widespread showers and thunderstorms, the NWS said. Some drying was possible after Tuesday, but small chances for mountain and desert thunderstorms may continue through the end of the week.

The shallow marine layer was expected to persist along the coast.

High temperatures along the coast Sunday are predicted to reach 81 degrees, 88 to 93 in the western valleys, 94 to 99 near the foothills, 91 to 98 in the mountains and 109 to 114 in the deserts, according to the weather agency.

Northwest winds with gusts around 20 knots may occur over portions of the outer coastal waters between 30 and 60 nautical miles offshore later Sunday afternoon and early evening.

City News Service contributed to this article.