At least six people are being treated for injuries related to one of the fires, a spokesperson for UCHealth told CNN. Kelli Christensen said no more information was available for the patients, who are at UCHealth Broomfield Hospital.
The towns — Louisville and Superior — are about 4 miles apart, not far from the city of Boulder.
The US Census Bureau says Louisville has about 21,000 residents and Superior has 13,000.
“We are in the midst of a truly historic windstorm across the front range, foothills and urban corridor,” said the National Weather Service office in Boulder.
Widespread wind gusts of 80-100 mph have been observed, the weather service said, and “a handful of sites in Rocky Flats have seen several hours worth of gusts 100-115 mph.”
County residents have been asked to evacuate if they see flames from one of multiple wildland fires.
The hurricane-force wind gusts being reported are being attributed to “exceptional mountain wave amplification,” which is a major increase in wind speed as air flows over and down the mountains into the lower elevations that can occur under very specific atmospheric conditions.
High-wind warnings are in effect for portions of Colorado and Wyoming through this evening. Sustained winds of 25 to 40 mph are forecast with gusts exceeding 80 mph.
The “strongest winds below 6000 feet are expected to be near the base of the foothills from Boulder north to Fort Collins to the Wyoming border,” the weather service said.
In addition to quickly spreading fires, these strong winds likely will blow down trees and power lines, which could lead to widespread power outages and difficult travel.
There will likely be a “rapid retreat of the strongest winds back into the foothills” by Thursday evening, the NWS office said.
“Prayers for thousands of families evacuating from the fires in Superior and Boulder County,” he tweeted.
CNN’s Haley Brink, Brando Miller and Steve Almasy contributed to this report.