National Weather Service United States Department of Commerce

Thunderstorms and Heavy Rain in the Mid-South; Heat Continues in the Southeast and Southwest

Severe thunderstorms and heavy rain are expected across portions of the mid-Mississippi Valley into the Ohio Valley and portions of Arizona. Dangerous heat persists in the South and Southeast while building into the Southwest. Overnight lows will be so warm that, when combined with oppressive dew points, little-to-no relief from the scorching daytime highs will be available. Read More >

COZ205-201100-
COZ205-201100-
Colorado River Headwaters-
1255 PM MDT Wed Aug 19 2026

Fire Weather Planning Forecast for Wrn Colorado and Ern Utah
National Weather Service Grand Junction CO
1255 PM MDT Wed Aug 19 2026

.DISCUSSION...

Hot and dry conditions continue in the valleys, while showers and
thunderstorms will develop on the mountains each afternoon. 
Critical fire weather is not expected. However, gusty outflow 
winds could pose hazards to crews. Relative humidities will trend 
above critical thresholds this weekend and beyond as shower 
coverage becomes more widespread. Flash flood risk will rise
each afternoon into the weekend.

...GUSTY ERRATIC WINDS CAN BE EXPECTED NEAR ANY SHOWERS
OR THUNDERSTORMS...
...THE SMOKE DATA IS CALCULATED FROM AN AVERAGE AT 6000 FEET MSL...


.TONIGHT...
Sky/weather.........Partly cloudy (40-50%). Isolated showers and 
                    thunderstorms until 2400. 
Chc of lightning....20 percent. 
Min temperature.....53-63 F. 
Max humidity........56-66%. 
20-foot winds.......Upslope/upvalley 4 to 8 mph becoming 
                    downslope/downvalley 3 to 6 mph by sunset.
CWR.................10 percent. 
15K Ft MSL Winds....Northwest 15 to 20 mph. 
Mixing Height.......7000 ft AGL until 2000, then 500 ft AGL. 
Transport Winds.....Northwest 5 to 10 mph until 2400, then 
                    southeast. 
Smoke dispersal.....Fair until 2100, then poor. 

.THURSDAY...
Sky/weather.........Mostly sunny (20-30%) until 1200, then partly 
                    cloudy (30-40%). Isolated showers and 
                    thunderstorms after 1200. 
Chc of lightning....20 percent. 
Max temperature.....80-90 F. 
Min humidity........14-24%. 
20-foot winds.......Downslope/downvalley 3 to 6 mph becoming 
                    upslope/upvalley 4 to 8 mph by 1100.
CWR.................10 percent. 
15K Ft MSL Winds....Northwest 15 to 20 mph decreasing to 10 to 15 
                    mph in the afternoon. 
Mixing Height.......1500 ft AGL until 1000, then 10500 ft AGL. 
Transport Winds.....Northwest 5 mph. 
Smoke dispersal.....Poor until 0900. Good after 1200. 

.THURSDAY NIGHT...
Sky/weather.........Partly cloudy (40-50%). Isolated showers and 
                    thunderstorms until 2400. 
Chc of lightning....0 percent. 
Min temperature.....53-63 F. 
Max humidity........48-58%. 
20-foot winds.......Upslope/upvalley 4 to 8 mph becoming 
                    downslope/downvalley 3 to 6 mph by sunset.
CWR.................0 percent. 
15K Ft MSL Winds....North 5 to 10 mph shifting to the west after 
                    midnight. 
Mixing Height.......8500 ft AGL until 1900. 500 ft AGL after 2000. 
Transport Winds.....North 5 to 10 mph until 2400, then southeast. 
Smoke dispersal.....Poor. 

.FRIDAY...
Sky/weather.........Mostly sunny (20-30%) until 1200, then partly 
                    cloudy (30-40%). Isolated showers and 
                    thunderstorms after 1200. 
Chc of lightning....10 percent. 
Max temperature.....82-92 F. 
Min humidity........12-22%. 
20-foot winds.......Downslope/downvalley 3 to 6 mph becoming 
                    upslope/upvalley 4 to 8 mph by 1100.
CWR.................10 percent. 
15K Ft MSL Winds....West 5 to 10 mph. 
Mixing Height.......2000 ft AGL until 1000, then 10000 ft AGL. 
Transport Winds.....Southwest 5 mph until 1200, then northwest. 
Smoke dispersal.....Poor until 0900. Good after 1200. 

.FORECAST FOR DAY 3 THROUGH 7...
.SATURDAY...Partly cloudy. Numerous showers and scattered
thunderstorms. Lows 51-61. Highs 77-87. Winds less than 15 mph. 
.SUNDAY...Mostly cloudy. Numerous showers and scattered
thunderstorms. Lows 49-59. Highs 73-83. Winds less than 15 mph. 
.MONDAY...Partly cloudy. Scattered showers and thunderstorms.
Lows 47-57. Highs 73-83. Winds less than 15 mph. 
.TUESDAY...Partly cloudy. Scattered showers and thunderstorms.
Lows 47-57. Highs 74-84. 
.WEDNESDAY...Partly cloudy. Scattered showers and thunderstorms.
Lows 47-57. Highs 75-85.