The National Weather Service has issued a flood watch for the Treasure Valley and surrounding areas because of potential excessive rainfall from Hurricane Hilary.

Hurricane Hilary, just off the northwest coast of Baja California Sur, weakened to a Category 3 on Saturday as it neared landfall in Mexico and the United States, which is expected to happen Sunday. A Category 3 hurricane is considered a major hurricane, with wind speeds between 111 - 129 mph.

Aside from the Boise area, several other southwestern Idaho cities are also under the flood watch including Caldwell, McCall, Stanley, Mountain Home and Twin Falls, according to the National Weather Service. A flood watch is issued when it seems likely that flooding could occur but is not a guarantee. Under a flood warning, flooding is about to happen or is actively occurring, according to the Weather Service website.

The Boise area is expected to receive up to an inch of rain from Sunday to Tuesday based on early predictions from the Weather Service, the Statesman previously reported. But, areas such as McCall could get up to 1.8 inches.

ADVERTISEMENT Advertisement

Rain showers and thunderstorms were developing across the Treasure Valley Saturday afternoon, with areas like East Boise already seeing some light rain, according to a post on X, formerly known as Twitter, from Boise’s National Weather Service. People should expect heavy rain, wind gusts that could go up to 50mph, and lightning, the post said.

The flood watch is in effect until Monday evening. In a post on X, Boise’s office of the National Weather Service predicted that the heaviest rain is expected to occur Sunday and Monday but there could be additional precipitation Tuesday. The post also said that strong winds are expected Monday.

The Weather Service said the excessive runoff from the rain could cause creeks, streams and other low-lying areas to flood. In its flood advisory, the Weather Service also warned that flooding may occur in areas with poor drainage and urban areas and are asking people to monitor the latest warnings.

With the arrival of significant tropical moisture Sun/Mon, a Flood Watch has been issued due to excessive rainfall and potential for flooding. While heaviest rain will occur Sun/Mon, additional precipitation is expected Tuesday. Strong winds are also expected Monday. #IDwx #ORwx pic.twitter.com/G7xkG6Eb4I — NWS Boise (@NWSBoise) August 19, 2023