The National Weather Service has 96 active weather alerts posted across 18 states Sunday, most of them Red Flag Warnings tied to a combination of wind, low humidity and dry fuels that is raising wildfire risk from the Pacific Northwest to the Midwest and mid-Atlantic.
Affected states include California, Colorado, Iowa, Idaho, Illinois, Indiana, Michigan, Minnesota, Missouri, Montana, North Dakota, Ohio, Oregon, Pennsylvania, South Carolina, South Dakota, Washington and Wisconsin.
In south-central North Dakota, the Weather Service warned of critical fire weather conditions through the afternoon and evening in Morton, Grant, Sioux and Emmons counties, with the Red Flag Warning running from noon CDT (11 a.m. MDT) until 9 p.m. CDT (8 p.m. MDT). Northwest winds were forecast to increase to around 25 mph, with higher gusts, on top of low relative humidity — the classic recipe the agency cites for rapid fire spread. A Fire Weather Watch elsewhere in the alert set has since been cancelled, an indication conditions are easing in at least that zone even as warnings persist elsewhere.
The fire weather threat is broadest across the Midwest. The sample of active alerts lists at least 48 Illinois counties, stretching from Jo Daviess and Stephenson in the northwest to Champaign and Vermilion in the east, and roughly 30 Indiana counties including Vigo, Monroe, Bartholomew and Marion. Wisconsin’s alerts extend onto Lake Michigan, covering Green Bay and the waters from Rock Island Passage to Sheboygan.
Smoke and particulate pollution are compounding the fire-weather picture. The Indiana Department of Environmental Management has declared an Air Quality Action Day in effect until midnight EDT, citing fine particulate (PM 2.5) levels expected to reach the “Unhealthy for Sensitive Groups” range. The agency is advising active children and adults, along with people with respiratory conditions such as asthma, to limit prolonged outdoor exertion.
The National Weather Service says a Red Flag Warning means critical fire weather conditions are either underway or expected imminently, driven by the combination of strong winds, low relative humidity and warm temperatures. Any spark under those conditions can spread quickly and become difficult to control. Mariners on the affected Great Lakes waters, meanwhile, are being told that less experienced boaters, especially those in smaller vessels, should avoid the water until conditions improve, and that anyone who must go out should proceed with caution and use proper fog signals.
With warnings covering states as far apart as Washington and South Carolina, the pattern reflects a widespread, multi-region dry spell rather than a single storm system, and forecasters caution that new red flag conditions could develop in additional counties as the pattern holds through the week.