Rain will greet Encinitas trick-or-treaters Saturday night as a pineapple express storm moves through San Diego County on Halloween.

The National Weather Service forecasts a 90% chance of showers for Encinitas on Saturday night, Oct. 31. The rain could be heavy at times, with a low around 63 degrees. The agency's point forecast for Encinitas calls for between a half inch and three-quarters of an inch of new rain Saturday night alone.

The storm, a pineapple express system that forms in the tropical Pacific, will begin producing significant rain early Saturday night during the height of trick-or-treating, the San Diego Union-Tribune reported. It will grow stronger around 1 a.m. Sunday, Nov. 1, and mostly fade by mid-morning. Saturday evening temperatures will be in the low to mid-60s.

What trick-or-treaters should know

Families heading out Saturday evening should bring umbrellas. 10News reported some rain could move in during the evening, though the heaviest downpours are expected later overnight.

Saturday daytime will be mostly cloudy with a high near 72, according to the NWS forecast. That means early trick-or-treaters may stay dry, but conditions will deteriorate as the evening goes on.

Sunday and beyond

Sunday brings another round. The NWS forecasts an 80% chance of showers for Encinitas with a high near 70 and another half inch to three-quarters of an inch of rain possible. Northeast winds of 10 to 15 mph will shift west in the afternoon.

Across San Diego County's coast and valleys, 10News reported rainfall totals of 0.70 to 1.25 inches are possible, with localized flooding a concern by Sunday morning. Gusty winds of 20 to 30 mph are expected along the coast overnight Saturday into Sunday. There is an outside chance of thunderstorms, according to the Union-Tribune.

Showers should taper off Sunday afternoon. By Sunday night, the chance of rain drops to 30% before 11 p.m. Monday's forecast calls for sunny skies and a high near 72.

Coastal flooding

The NWS had a Coastal Flood Advisory in effect for Encinitas through 2 p.m. Friday, Oct. 30. Whether additional coastal flood advisories will be issued in connection with the storm's rainfall and runoff was not clear as of Friday.