Last day of average temperatures before cool down

SAN DIEGO (KUSI) — Temperatures are expected to be about average Tuesday across San Diego County before a low-pressure system lingering off the coast moves in Wednesday to bring significantly cooler weather.

There will be a slight chance of rain and thunderstorms Tuesday in the mountains and deserts, while light showers could pop up west of the mountains Wednesday night, Thursday and Friday morning. Patchy clouds and fog are expected along the coast Tuesday, with denser clouds moving in with the low-pressure system beginning Wednesday.

High temperatures Tuesday will be 73 to 78 degrees at the beaches, 81 inland, 81 to 86 in the western valleys, 86 to 91 near the foothills, 84 to 91 in the mountains and 102 to 107 in the deserts.