HELENA — Weather conditions had an immediate effect on the Mann Gulch Fire from months before to the moment firefighters took their last breath. On August 4th, 1949, lightning sparked numerous wildfires in the Helena National Forest. Much of the western United States was sweltering under a record-setting heat wave on top of several months of drought.
On August 5th, 1949, a group of smokejumpers left Missoula to fight one of the new wildfires along the Missouri River, the last fire most of this group would ever fight.
Weather conditions battled these men right from the start, as wind on the flight over was turbulent. One smoke jumper got sick on the flight and did not jump, returning with the plane to Missoula. The firefighters noted cumulonimbus clouds developing as they flew, which is a sign of atmospheric instability. Upon jumping out of the plane, the wind scattered the men and their equipment farther apart than expected.
There were no official weather observations or recordings of the conditions that day in Mann Gulch, but it was hot, dry and windy throughout the area. That day in Helena the high was 97 F, wind gusted up to 32mph, and the humidity fell to 16%, red flag warning weather.
A strong south wind created turbulent conditions near the mouth of the canyon of Mann Gulch, and fire spotting and fire whirls ignited new spot fires that cut off the firefighters' escape to the safety of the Missouri River. At this point, the fire blew up in the peak afternoon heating and wind. At that time, the Haines Index that's used to estimate potential fire growth was at the top of the charts. Conditions that high only happen on 2% of August days, making the situation extreme and rare.
It is estimated that the intense flames covered nearly 3,000 acres in only ten minutes, a race that 13 firefighters could not win. Ultimately, it took 450 men fighting the Mann Gulch fire for five more days to get the blaze under control.
It was a tragic and fateful day, and a reminder of the harsh conditions these brave souls and every firefighter can face while protecting our lives and property.
