An anomalously strong upper-level ridge is building over the Desert Southwest and Great Basin, driving temperatures into record-breaking territory through the week with dry conditions and light winds expected to persist through Saturday before a gradual cooling trend begins.
Currently, mostly cloudy skies are in place across the area with afternoon rain and snow showers ongoing across the northern part of the region. Snow levels are hovering between 7,000 and 8,000 feet with accumulations expected to remain under a tenth of an inch. These conditions will change dramatically over the next 24 to 48 hours as the ridge takes control.
Temperatures will climb steadily from slightly above normal today to 10 to 20 degrees above normal Tuesday and 15 to 25 degrees above normal Wednesday. High temperatures Tuesday will already be close to record-breaking, with confidence of actually breaking records increasing Wednesday onward. Breezy to gusty afternoon winds of 20 to 35 mph in the Snake Basin east of Boise today and Tuesday are worth noting, along with a 5 to 10% chance of rain showers across northern zones Tuesday morning and afternoon.
The heat peaks Thursday and Friday with highs near 80 degrees under mostly sunny skies and light winds. This is an unusually warm weather pattern for mid-March, driven by an anomalous high-amplitude upper-level anticyclone dominating the western United States. Daily temperature records will be threatened at sites across southwestern Idaho and southeastern Oregon.
The pattern will begin to change by Saturday as upper-level flow transitions to a more zonal west-to-east pattern. Temperatures will be cooler on Saturday by about 5 degrees, dropping another 5 degrees or so Sunday, and continuing to cool into Monday. While there is some uncertainty in the exact timing of the cooling trend, the overall direction is clear - the exceptional heat will gradually give way to more seasonal conditions heading into next week.
Residents should take this heat seriously despite the calendar saying March. Stay hydrated, limit strenuous outdoor activity during peak afternoon hours, and check on elderly neighbors and family members who may be more vulnerable to the heat.
Tonight
Mostly cloudy, then gradually becoming clear, with a low around 41. Light wind.
Tuesday
Sunny & milder, with a high near 72. Light wind.
Tuesday Night
Partly cloudy, with a low around 46. Light and variable wind.
Wednesday
Sunny & unseasonably warm with record heat likely, with a high near 78. Light and variable wind.
Wednesday Night
Mostly clear, with a low around 49. Light and variable wind.
Thursday
Sunny with record heat, with a high near 80.
Thursday Night
Partly cloudy, with a low around 52.
Friday
Mostly sunny with record heat continuing, with a high near 80.
Friday Night
Mostly cloudy, with a low around 52.
Saturday
Partly sunny, a breeze & not as warm, with a high near 72.
Saturday Night
Mostly cloudy, with a low around 44.
Sunday
Partly sunny & cooler, with a high near 64.
Sunday Night
Partly cloudy, with a low around 41.
Monday
Partly sunny, with a high near 65.
