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Winter Air Quality Update & Forecast
Monday, December 23, 2019 11:26 AM

Locations and Air Quality Conditions

Current Situation Forecast
Air Quality in Seeley Lake reached UNHEALTHY level but is now at UNHEALTHY FOR SENSITIVE GROUPS. Elsewhere across the state, air quality is mostly GOOD with a few locations reporting MODERATE levels. With a low sun angle and little to no wind, Seeley Lake will struggle to break out of the inversion today. In the Helena, Libby and Frenchtown, inversions have kept the air quality level at MODERATE, but these areas are on the lower end of concentrations, and may reach GOOD level today if there is enough warming to allow for vertical mixing.

Check Today’s Air for current conditions.
Air quality may improve this afternoon in Helena and Frenchtown, where inversions are not quite as strong. Any improvements in Seeley Lake’s air quality this afternoon will likely be short-lived as was the case this weekend. Early sunsets and cold temperatures create conditions for strong inversions. No strong, organized weather systems are expected to move through for the next few days. Overall, Montana will stay dry this week. Some light snow flurries are possible late Tuesday/ Wednesday, mainly in western Montana, but accumulation totals will be low. A broad trough pattern will continue over the Southwest for the next few days, while Montana’s weather will stay quiet and stagnant. The next big change in weather looks to arrive this weekend, after the low-pressure system over the southwestern United States moves eastward. As this low moves out, northwesterly flow will set up over Montana, which will bring increased winds and improved dispersion, especially in the eastern half of the state.

Air Quality Bureau
Montana Department of Environmental Quality
Phone: (406) 444-3490




Real time particulate information is currently available in most of the larger urban areas from MTDEQ's Today's Air website.

Today's particulate report below compares particulate levels received from DEQ's
reporting stations with MTDEQ’s Health Effect Categories.

Locations and severity of PM 2.5 particulate values over the past 24 hours from the time above.
Health Effects Categories City
  Very Unhealthy  
  Unhealthy for Sensitive Groups  Seeley Lake

 Helena, Frenchtown, Libby 


 All other reporting locations. 

B1(x) One-hour BAM value (number of values)
B8(x) Eight-hour average BAM
B24 24 hour  average BAM value