National Weather Service United States Department of Commerce

Storms and Heavy Rainfall in the Plains and Southern Appalachians; Hazardous Heat in the South and Southeast

Severe thunderstorms with heavy rainfall will be possible across the southern Appalachians through this evening. Thunderstorms are also expected from the northern/central Plains into portions of the Midwest through Tuesday, and severe storms may produce large hail and damaging wind gusts. Meanwhile, hazardous heat persists across the South and Southeast. Read More >

COZ205-181100-
COZ205-181100-
Colorado River Headwaters-
1247 PM MDT Mon Aug 17 2026

Fire Weather Planning Forecast for Wrn Colorado and Ern Utah
National Weather Service Grand Junction CO
1247 PM MDT Mon Aug 17 2026

.DISCUSSION...

Relative humidities continue to approach critical values each 
afternoon this week. However, winds remain below thresholds as a 
rule of thumb. Some stronger gusts develop Tuesday and Wednesday, 
but widespread critical fire weather conditions are unlikely. 
Terrain based showers develop Tuesday and beyond with wetting rain
chances increasing as the week continues. Gusty outflows and dry 
lightning could threaten before deeper monsoonal moisture arrives 
late week.

...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 (30-40%). 
Chc of lightning....0 percent. 
Min temperature.....51-61 F. 
Max humidity........35-45%. 
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....West 10 to 15 mph increasing to 15 to 20 mph 
                    after midnight. 
Mixing Height.......9500 ft AGL until 2000, then 500 ft AGL. 
Transport Winds.....Southwest 5 mph. 
Smoke dispersal.....Fair until 2100, then poor. 

.TUESDAY...
Sky/weather.........Partly cloudy (40-50%). Isolated showers and 
                    thunderstorms after 1200. 
Chc of lightning....10 percent. 
Max temperature.....77-87 F. 
Min humidity........13-23%. 
20-foot winds.......Downslope/downvalley winds 4 to 8 mph becoming 
                    west 10 to 15 mph with gusts to 25 mph in the 
                    afternoon. 
CWR.................10 percent. 
15K Ft MSL Winds....West 20 to 25 mph. 
Mixing Height.......1000 ft AGL until 0900. 11000 ft AGL after 
                    1000. 
Transport Winds.....West 5 to 10 mph. 
Smoke dispersal.....Poor until 0900. Excellent after 1200. 

.TUESDAY NIGHT...
Sky/weather.........Partly cloudy (40-50%). Isolated showers and 
                    thunderstorms until 2400. 
Chc of lightning....10 percent. 
Min temperature.....52-62 F. 
Max humidity........50-60%. 
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....West 20 to 25 mph. 
Mixing Height.......10000 ft AGL until 1900. 500 ft AGL after 2000. 
Transport Winds.....Northwest 5 to 10 mph until 2400, then south. 
Smoke dispersal.....Fair until 2100, then poor. 

.WEDNESDAY...
Sky/weather.........Mostly sunny (20-30%) until 1200, then partly 
                    cloudy (40-50%). Isolated showers and 
                    thunderstorms after 1200. 
Chc of lightning....20 percent. 
Max temperature.....76-86 F. 
Min humidity........17-27%. 
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 20 to 25 mph decreasing to 15 to 20 
                    mph in the afternoon. 
Mixing Height.......1500 ft AGL until 0900. 10000 ft AGL after 
                    1000. 
Transport Winds.....West 5 mph until 1200, then northwest 10 to 15 
                    mph. 
Smoke dispersal.....Poor until 0900. Very good after 1200. 

.FORECAST FOR DAY 3 THROUGH 7...
.THURSDAY...Mostly clear. Isolated showers and thunderstorms.
Lows 49-59. Highs 78-88. Winds less than 15 mph. 
.FRIDAY...Mostly clear. Isolated showers and thunderstorms. Lows
50-60. Highs 79-89. Winds less than 15 mph. 
.SATURDAY...Partly cloudy. Scattered showers and thunderstorms.
Lows 51-61. Highs 77-87. Winds less than 15 mph. 
.SUNDAY...Partly cloudy. Scattered showers and thunderstorms.
Lows 49-59. Highs 74-84. 
.MONDAY...Partly cloudy. Scattered showers and thunderstorms.
Lows 48-58. Highs 72-82.