Halloween forecast: dry treats for the East, wet tricks for the West and parts of the South

For most of the country, Halloween falls on a dry, seasonably cool Saturday — but families in the West, parts of the South, and stretches of the Midwest are facing a different night entirely, with rain, thunderstorms, and even mountain snow threatening to complicate trick-or-treating.

The clearest story is in the West, where a moisture-laden Pacific system is pushing rain into California, Nevada, Oregon, and Arizona. San Diego is on track for its first measurable Halloween rain in 39 years — the last was in 1987, according to the National Weather Service. The NWS noted that Palm Springs and Riverside, California are in the same boat. 'It has been 30-40 years since many of our cities have seen a rainy Halloween,' the National Weather Service in San Diego posted on X.

Most major Southern California metro areas are expected to receive less than one inch of rain, according to AccuWeather senior meteorologist Alex Sosnowski. Phoenix may largely dodge the worst of it: the rain forecast there is expected to hold off until very late Halloween night, likely after trick-or-treating wraps up, according to the Spokesman-Review. In the Sierra Nevada, the precipitation could fall as snow.

The rain hitting the Southwest is part of an unusually wet pattern, partially fueled by tropical moisture from an atmospheric river known as the Pineapple Express, according to AccuWeather. NOAA's Weather Prediction Center warned that 'much of this region is highly susceptible to rainfall given how wet it has been lately,' and flagged scattered flash flooding anticipated over central Arizona on Saturday, with the heavy rainfall threat ramping up over the Four Corners on Sunday.

Scattered flash flooding is anticipated over central Arizona tomorrow [Saturday], before the heavy rainfall threat ramps up over the Four Corners on Sunday.— NOAA Weather Prediction Center

In the Bay Area, the picture is less dramatic but still chilly. The National Weather Service said there is a slight chance of light rain, especially Saturday daytime into Saturday night, with temperatures expected to run up to 10 degrees below seasonal norms. Oakland, San Mateo, and San Francisco are not expected to exceed 63°F, with overnight lows in the North Bay likely dropping into the low 40s.

Light rain at the heaviest. Any rain that falls will be extremely light. Very cold.— Roger Gass, NWS meteorologist

Even in parts of the Northwest where rain or snow stays away, temperatures in Montana, Idaho, Wyoming, eastern Washington, and eastern Oregon will be in the 30s and 40s, according to AccuWeather — cold enough that costume choice matters.

In the South, scattered showers and thunderstorms are possible Saturday evening, centered on the lower Mississippi Valley. AccuWeather predicts thunderstorms may accompany downpours in some communities from South Texas to southern Arkansas, including Houston and New Orleans. Florida, except for the peninsula, should stay dry; some spotty showers are possible there.

The Midwest gets relatively pleasant evening temperatures — 50s or 60s in most areas — but is not entirely clear. Showers and possibly thunder are forecast from parts of Nebraska and Kansas into the Lower Ohio Valley, and light, short-lived showers are possible in the Dakotas, Minnesota, Wisconsin, and the Upper Peninsula of Michigan, according to Weather.com meteorologist Jonathan Erdman.

The Northeast is the clear winner. High pressure is in control, bringing no rain or snow, manageable winds, and temperatures that are pleasant by late-October standards. The main advisory for families there: kids may need a warmer costume or jacket once the sun goes down, especially in New England.

Fortunately, we don't have a major storm in the forecast Saturday. But there may be weather headaches for some.— Jonathan Erdman, senior meteorologist, Weather.com

No single national storm is driving the disruptions — the issues are regional and scattered, meaning the practical advice varies sharply by location. Families in affected areas are advised to carry umbrellas or rain jackets, layer costumes for warmth, and check local forecasts before heading out Saturday evening.

Why it matters — With tens of millions of children trick-or-treating Saturday evening, knowing which regions face rain, cold, or flooding risk — and which don't — is the difference between a ruined costume and a dry, safe night out.

Reported by weather.com, forbes.com, patriotledger.com, spokesman.com, mercurynews.com