Trick-or-treaters will have to get out early to miss a storm front, which will probably pass through northern Utah about 7 to 10 p.m. Wednesday evening.

Meteorologist Ray Collins of the Salt Lake office of the National Weather Service, said there will be a chance of showers developing along the mountains or higher bench areas between 5 and 7 p.m. Wednesday.Meanwhile, mild weather continued over Utah Tuesday, with high temperatures in the mid-70s in the Salt Lake, Ogden and Provo areas. But a trough of low pressure is strengthening in the eastern Pacific Ocean. And tropical storm Trudy, which was located about 800 miles south of Los Angeles early Tuesday, is shifting northward, said Edward R. Carle, a forecaster at the weather service.

Forecasts show tropical moisture from Trudy and the strong low-pressure system continuing through at least Friday.

Carle said it is too early to say Utah will receive large amounts of moisture. But the storm will likely result in much colder temperatures and periods of rain in the valleys and snow in the mountains by Thursday.