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Everyone knows that fires are a big concern during droughts, but can they also cause a drought elsewhere? I currently live just on the East side of the Canadian Rockies. All summer long fires have been burning in British Columbia and in Montana, and we've been down wind catching all of the smoke. We have not had a single significant day of rainfall all summer long. It rained a little only once overnight a few weeks back from what I can recall.

My best guess is that the smoke and heat from the fires is somehow drying out the air before it reaches the continental divide, preventing any kind of rain fall.

Can forest fires cause droughts significant distances downwind? If so, how?

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    I'll leave it to someone else to summarize and find other supporting evidence, but in a nutshell their conclusion is that smoke does have an effect on local weather and rainfall. onlinelibrary.wiley.com/doi/10.1002/2013JD019860/full. Of course, climate and longer term patterns like droughts also significantly affect outcomes.
    – Matthew Wetmore
    Aug 25, 2017 at 20:18
  • @Paparazzi Ever heard of cloud seeding? Precipitation needs a nuclei before it can condense. With the amount of ash going up into the air I wouldn't be surprised if the ash was rising hot, soaking up humidity, then falling to the ground moist, preventing that humid air from forming clouds and precipitating further down wind. Last time there was a drought in BC, it rained buckets on the other side of the mountains, because all water got soaked up by the sun in BC and the clouds dumped the moisture as they rose over the highest mountains coming into Alberta.
    – ShemSeger
    Aug 25, 2017 at 21:15
  • BC rain is produced by air currents out in the Pacific and are generally not rain bearing during the peak forest fire times. Kamloops is officially a desert, as well as many other areas in BC.
    – Ken Graham
    Aug 25, 2017 at 22:31
  • @Paparazzi I wouldn't be surprised if it did, one of the questions I'm asking is would it do it sooner than later? Does the smoke cause precipitation to fall prematurely, preventing it from from falling where it normally would in it's typical cycle?
    – ShemSeger
    Aug 26, 2017 at 13:58
  • @KenGraham: No surprise there, given that rain tends to have a dampening effect on forest fires.
    – Vikki
    Feb 15, 2022 at 8:40

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There is a huge high pressure ridge (588+DAM) that has been parked over a good share of the Intermountain West (centered in various parts of the Great Basin) all summer. Storms that ride over the ridge to the north and then come down on the east side of the clockwise circulation will be where the rainfall occurs. The smoke itself if anything will contain water vapor, and indeed pyroclastic clouds can cause rainfall in their vicinity. But as for drought downwind, no. Heat islands in cities can clearly change rainfall patterns (such as Atlanta), but not the smoke. The fire season has been very active (nifc.gov) on both sides of the border.

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  • Could the heat from the fires create a heat island?
    – ShemSeger
    Aug 29, 2017 at 20:42

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