Unseasonably cold temperatures, ‘exceptional’ rainfall in Boise’s forecast for Monday
An unusual storm system will bring unseasonably cold temperatures and noteworthy precipitation to southwest Idaho on Monday, with snow expected to fall in the mountains and rainfall in the Treasure Valley potentially breaking a 79-year-old record, according to weather experts.
Jay Breidenbach, a meterologist with the National Weather Service in Boise, told The Statesman in a phone interview that closed-off low-pressure system will move over the Treasure Valley on Monday from the northwest, bringing with it moisture and cold temperatures. The National Weather Service is predicting a high in the Boise area of 60 degrees Monday, which Breidenbach called “near the coldest temperature we’ve ever had for this time of year.”
“That’s going to be 20 to 30 degrees below normal,” he said. “It should be a record low high temperature (for the day).”
In a Sunday news release, the National Weather Service also said it’s predicting “exceptional amounts” of rain in the region, prompting flash flood warnings through Monday night in the west-central Idaho Mountains the the Owyhees. McCall could see about an inch of rain, while places like Yellow Pine and Riggins could see as much as 1.5 inches.
In the Boise area, forecasts are calling for about a half-inch of rain — just enough to break the area’s longstanding precipitation record for the month of June. As of Sunday, 2.92 inches of rain had fallen in the Boise area. In an average June, Boise sees about .69 inches of precipitation, but several wet storms early in the month vaulted June 2020 toward record status. The all-time June rainfall record for Boise is 3.41 inches, which last occurred in 1941, Breidenbach said.
“If we get half an inch — and we’re forecasting around half an inch — we’ll break that record,” Breidenbach said.
He said showers will start early Monday and continue in light to moderate showers through the day.
In addition to rain, snow is expected to fall in the mountains above 7,000 feet in elevation. Breidenbach said the Sawtooths will “feel like winter,” while a light dusting is expected in mountains closer to Boise.
“I wouldn’t be surprised if Shafer Butte gets a little bit of snow up on the top of it,” Breidenbach said.
The cold snap will leave as quickly as it rolled in, Breidenbach said. Temperatures are forecast to be back in the 70s by Tuesday and will continue to rise to the 90s by the weekend.
“As unusual as that weather is, we’re going to be right back up to that late June/early July heat here in Boise,” Breidenbach said.
This story was originally published June 28, 2020 at 3:20 PM.
