SAN DIEGO — Don’t put your coats and umbrellas away yet: San Diego is in for a “rollercoaster” week, according to the National Weather Service, with high temperatures forecasted to transform into a major cooldown and chance of rain.

NWS said a low pressure system moving south from the Gulf of Alaska will be affecting the region for much of the next week.

While Sunday will see a slight dip in temperatures, it will remain fairly warm across the county.

Daytime highs in the coastal neighborhoods on Sunday will be in the high 60s, while valley and mountain communities are forecasted to see maximum temperatures in the mid to high 70s. Desert areas could see heat anywhere from the high 80s to the low 100s.

A thick marine layer will accompany the biggest drop in temperatures on Monday. Most areas away from the deserts will see anywhere from a 5 degree to 10 degree departure from normal high temperatures.

The marine layer will also bring a chance of precipitation in the middle of the week, with patchy drizzle possible as early as Tuesday. More widespread showers are likely on Wednesday and Thursday.

NWS said that the strongest chance of precipitation will come Wednesday night into Thursday. Both morning and evening commutes could be impacted, according to the weather agency.

About a quarter to a half of an inch is possible west of the mountains, NWS said. In the south slopes of San Bernardino County, up to one inch of rain is possible. Measurable snow is possible for elevations above 6,000 feet.

Periods of gusty winds are also possible across the mountains and deserts moving into the week, according to NWS.