An incoming atmospheric river is expected to bring widespread rain and potential flooding to parts of Utah and Colorado over the Halloween weekend, according to the National Weather Service. The moisture plume, which is tapping into Pacific moisture, is forecast to produce heavy rainfall in southeast Utah and southwest Colorado by Sunday.
Atmospheric River Brings Heavy Rain
The National Weather Service Grand Junction issued a hydrologic outlook noting that low pressure is expected to begin digging southward from the Pacific Northwest on Friday. This weather pattern will evolve into an atmospheric river streaming into the Desert Southwest over the weekend. While showers and thunderstorms are expected to develop on Friday and Saturday, the National Weather Service warned that a few thunderstorms could produce impactful downpours due to saturated soils left over from historic rainfall last weekend.
Flood and Debris Risks
Deeper moisture is expected to develop Saturday night and early Sunday, leading to heavier and more widespread rainfall across southeast Utah and southwest Colorado. The National Weather Service Grand Junction noted that rainfall amounts between 1 to 2 inches are possible for portions of these areas. Although rivers are forecast to remain below action stage, there is growing concern regarding runoff from saturated hillsides. This could trigger rock, mud, and debris flows onto roadways, as well as impacts in flash flood-prone burn scars, washes, slot canyons, and arroyos.
Saint George Forecast Details
In Saint George, the National Weather Service forecast for October 29, 2026, indicates a mostly cloudy day with a high near 73. Precipitation chances increase significantly heading into the weekend. Friday shows a 40 percent chance of showers and thunderstorms, while Friday night carries a 60 percent chance of rain, particularly between 9pm and midnight. Saturday is expected to be partly sunny with a 20 percent chance of rain before 3pm and a 20 percent chance of showers or thunderstorms after 3pm. By Saturday night, the chance of rain rises to 80 percent, with new precipitation amounts expected between a tenth and a quarter of an inch.
Weekend Weather in Saint George
The weather in Saint George on Sunday is expected to include rain before noon, followed by showers and possible thunderstorms after noon, with a 90 percent chance of precipitation. High temperatures for the day are forecast near 64. Rainfall amounts for Sunday could reach between a quarter and a half of an inch. The weather is expected to clear up by Monday, which is forecast to be sunny with a high near 64.
Park City Weather Outlook
In Park City, the National Weather Service forecast for October 29, 2026, predicts a partly sunny day with a high near 56. Rainfall chances in the area include a 20 percent chance of rain after 3pm on Friday, followed by a 50 percent chance of rain on Friday night. Saturday is expected to be mostly cloudy with a 40 percent chance of rain, including a slight chance of showers and thunderstorms between noon and 3pm and after 3pm.
Snow and Rain in Park City
The weekend weather in Park City will intensify on Sunday, with a 100 percent chance of rain. The forecast predicts rain before noon, rain showers between noon and 3pm, and rain that may be mixed with snow showers after 3pm, with thunder also possible. Temperatures in Park City on Sunday are expected to reach a high of 43. By Sunday night, the forecast predicts rain and snow showers, becoming all snow after midnight, with a low around 32. Monday is expected to bring a chance of snow, primarily before noon, with a high near 41.
Salt Lake City Airport Forecasts-100% Chance of Rain on Sunday, with a high near 53. The forecast for Sunday includes showers and the possibility of a thunderstorm, with rainfall amounts between a half and three quarters of an inch possible. On Monday, there is a chance of rain before noon, with a high near 50.
Salt Lake City International Airport is also expected to experience wet weather. The National Weather Service forecast for October 29, 2026, shows a partly sunny day with a high near 63. A 20 percent chance of rain is expected after 3pm on Friday, followed by a 40 percent chance of showers and thunderstorms on Friday night. Saturday carries a 30 percent chance of rain, including a slight chance of showers and thunderstorms between noon and 3pm and after 3pm, with a 60 percent chance of rain and possible thunderstorms on Saturday night.
