- Current Fire Activity Increasing: Fire activity continued to increase significantly across the West during July. The onset of the seasonal monsoon effectively moderated fire activity in the Four Corners Region, while warm temperatures fueled large and damaging wildfires in California and the Pacific Northwest. The Dixie Fire in California has become the second largest wildfire in state history, destroying over 1000 structures with an additional 15,000 threatened.
- Excessive Heatwaves Fueling Canada Wildfires: A series of heat waves has affected Western Canada over the summer months, deepening the drought, and fueling wildfires across the region. Fire activity is elevated, with conditions expected to worsen in the coming weeks with an outlook of much above average temperatures.
- Smoke affecting air quality across North America: Smoke from Western US and Canada wildfires has been causing a deterioration of air quality across the continent. The city of Denver, CO experienced the worst air quality of any city in the world during the first weekend of August, while air quality and health alerts were issued as far east as Toronto and Philadelphia.
Current Wildfire Activity and Associated Impacts
Large fire activity and extreme fire behavior continue in 14 states across the western US, most notably in California, Montana, Oregon, Washington and Idaho. Hot temperatures and below average precipitation have caused fuels to dry out and vegetation is primed for ignition and spread of fire. While over 3.7 million acres have burned so far this year, this is slightly below the 10 year average of 4.3 million acres that has typically burned by mid August. However, the fires that are burning have been damaging and in some cases, record setting.
The Dixie Fire (inclusive of the merged Fly Fire) in the Sierra Nevada Mountains in Northern California has burned over 500,000 acres, making it the second largest wildfire in California history. 1,109 structures have been destroyed since it ignited on July 13th. Hot, dry and windy conditions caused rapid runs of the fire and extreme fire behavior that made fire fighting difficult. Overnight, winds generated by the fire complex itself allowed the fire to spot close to the communities of Clear Creek and Westwood. The fire is 30% contained, however 15,000 structures remain threatened and mandatory evacuations are in place. This area is considered to be at above baseline risk for wildfire from current climate conditions, which have been hot and dry. Historically, this region has been at above baseline risk during the previous drought period lasting from 2014 to 2016, and is now much above baseline risk again moving into late summer.
Guy Carpenter Wildfire Climate Adjustment Risk Score showing climate conditions favor above average wildfire risk across much of the Western US. Source: Guy Carpenter
Time Series of the Wildfire Climate Adjustment Risk Score for the area of the Dixie Fire showing climate conditions favor above average wildfire risk moving into late summer . Source: Guy Carpenter
Outside of California, the most wildfires in the US are burning in Montana, where the Richard Spring Fire has burned over 150,000 acres in the southeast corner of the state. Communities and infrastructure are threatened, and the fire is experiencing rapid runs and erratic behavior due to gusty winds and high temperatures. Additional fires are burning in the Pacific Northwest, where excessive heat advisories are in place across Washington and Oregon. Air quality alerts due to smoke are affecting communities from the west coast to the Rocky Mountains.
Currently burning fires and smoke footprint for the western United States . Source: US EPA
In Canada, the Okanagan Region in British Columbia has been particularly affected by wildfires this season, with many expected to burn until winter due to the deep state of drought the region is in, and an outlook of high temperatures and low precipitation. More than 557,000 hectares of land have burned across British Columbia in comparison to a 10-year average of 122,000 hectares. About 70% of fires have been lightning caused, and with August being very lightning prone, there is concern for more ignitions.
Currently burning fire locations and perimeters in Western Canada . Source: Environment Canada
Late Summer Wildfire Outlook
Above average temperatures are forecast for much of the western and northern United States for the next three months with normal to below normal precipitation forecast for much of the same region. These conditions will exacerbate the ongoing severe drought conditions covering much of the western United States and increase the likelihood of above normal significant wildfire activity. Fuel moistures have dropped to critically, and in some cases, historically low levels at many locations across the western United States resulting in extreme fire behavior and quick spread of fires following ignitions. Significant wildfire potential is expected to return to normal for much of the northern Great Plains and Pacific Northwest through October and November with above normal significant wildfire potential persisting across northern California and coastal southern California through November. Above normal significant wildfire potential is expected to develop for the southeast United States beginning in October, although this is dependent on tropical cyclone precipitation affecting the area in the coming months.
In Canada for the rest of August much of Ontario and Manitoba are expected to experience above average fire severity conditions with well above average fire severity conditions expected for western Ontario. In September, above average fire severity conditions will be present for western Ontario, much of the Prairies, and southern British Columbia with well above average fire severity conditions expected in southern Manitoba.
It should be noted that these forecasts of significant wildfire potential and fire severity are relative to the regional and seasonal baseline conditions and do not consider the small scale and short term meteorological factors that can significantly influence fire conditions.
Above average temperatures are forecast across much of the US for the next three months. Source: NOAA.
NIFC Wildland Fire Potential Outlook for the next 4 months. Source: Predictive Services
Canada Fire Danger Rating. Source: Environment Canada