Longtime residents of the northern Rocky Mountains may recall a severe cold snap that occurred frequently around the third week of August – most notably in 1992, when the temperature fell near zero five times and the first snow on record blanketed Great Falls – more than eight inches.
Research from 2008 found that a longstanding folklore among Montana firefighters is actually a legit weather phenomenon. It’s known as the “August Singularity” and it may have implications for the wildfire season.
The American Meteorological Society Glossary defines a singularity as “a characteristic weather condition that tends to occur on or near a specific date more frequently than chance would indicate.”
The best-known singularity in the western United States is the southwest monsoon season.
National Weather Service Great Falls Incident Meteorologist Bob Hoenisch points out another well-known singularity: “The most popular and well-known singularity is the January thaw you hear about in the northeastern United States. United. It’s similar in that sense, in that it’s the opposite of what you would normally see at this time of year.”
The study, led by North Carolina professors Peter Soulé and Paul Knapp, found a significant temperature swing around the third week of August – at times up to 40 degrees below seasonal norms.
In 2021, on August 18, the temperature soared to just 48 degrees and Great Falls saw over an inch and a half of precipitation over a two-day period. The normal high temperature for August 18 is 83 degrees.
As seen in recent years, the fire season extends well into the fall. The August Singularity can be a big help for firefighters, but it’s not the end of fire season. “It’s coming a little too early to be an end-of-season weather event. It’s more of a downturn in the season,” says Bob Hoenisch.