A dry weather system moving through the Great Basin is expected to shave a few degrees off typical temperatures across southern Arizona this weekend and into early next week, but forecasters say the more immediate concern will be gusty winds and very low humidity that elevate the risk of wildfires. Local weather officials have designated a First Alert Weather Day for Sunday as the system arrives and pushes breezy conditions into the region.
A Red Flag Warning is scheduled to run Sunday from 11 a.m. to 11 p.m. The warning cites gusty winds combined with very low relative humidity that will lead to elevated fire danger across the warned area. The advisory specifically applies to terrain below 5,500 feet east and south of Tucson, where officials expect the greatest threat of wind-driven fire behavior during the warning period. Statewide alert graphic showing a Red Flag Warning in southeast Arizona — including the Tucson area — as part of the First Alert forecast for elevated fire danger.
Forecast details for the immediate period call for a slight cooldown overnight, with tonight expected to be clear and a low near 62 degrees. Sunday is forecast to be sunny with a high near 90 and notably windy conditions that contribute to the heightened fire risk; Sunday night is expected to return to clear skies and a low around 61. Monday should remain on the cooler side, still below seasonal averages, with a daytime high near 87 and a clear night dropping to about 59 degrees.
Fire-weather outlooks show the threat increasing into tomorrow, with charts indicating conditions ranging from elevated to critical in terms of fire potential during the Red Flag period. Those graphics accompanying the forecast underscore the combination of gusty winds and low humidity that forecasters say will support rapid fire spread where ignition occurs. Fire weather level chart for tomorrow (Elevated to Critical), a forecast graphic highlighting the increased risk of fires during the Red Flag period.
By midweek the region is expected to return to a warmer pattern. Tuesday is projected to be partly cloudy with a high around 90 and a mostly clear Tuesday night with a low near 61. Wednesday climbs into the low-to-mid 90s with mostly sunny skies and a high near 94, followed by a mostly clear Wednesday night with a low around 62. Forecasts through the end of the workweek show continued sunshine and warming, with Thursday and Friday highs around 95 and overnight lows in the low 60s.
The Red Flag Warning applies to specific stretches of southern Arizona terrain both east and south of Tucson at elevations below 5,500 feet. The warning period is confined to the eleven-hour window on Sunday and is tied to the short-lived passage of the dry system across the Great Basin and into the Desert Southwest. Outside of that window, the current forecast calls for a return to drier, sunnier conditions as temperatures moderate upward by midweek.
The broader First Alert forecast summarizes the coming days as a mix of clear nights and mostly sunny daytime hours, punctuated by a brief stretch of breezy, fire-prone weather on Sunday. The immediate temperature trend shows a modest dip through Monday followed by a rebound that pushes highs into the 90s by Wednesday and sustains near-95-degree readings into Thursday and Friday. The forecasted overnight lows through the period range from the upper 50s to the low 60s.
Forecasters have emphasized the timing and geography of the warning: the Red Flag Warning is in place Sunday from 11 a.m. to 11 p.m. for gusty winds, very low humidity and elevated fire danger, and it includes areas below 5,500 feet east and south of Tucson. Outside of the elevated fire-risk window on Sunday evening, the region can expect generally clear skies and a warming trend through the latter half of the week, with daytime temperatures settling into the low- to mid-90s and overnight readings largely in the 50s and 60s.