The Greenwood Fire, that is ablaze in north-eastern Minnesota,  grew more than double in size on Tuesday. The wildfire has grown to more than 19,000 acres, producing pyro cumulous clouds that generated lightning and even raindrops, fire officials said.

The fire was detected on August 15 and is believed to have been sparked by lightning.

Most of the growth of the wildfire happened on Monday afternoon, prompting firefighters to leave McDougal Lake, about 80 miles northeast of Duluth. Authorities fear that structures near the area might have been destroyed or damaged by the fire.

"We had crews embedded, and as this fire took off, it was quite an effort to communicate with forces on the ground so they could get out," federal fire incident spokesperson Clark McCreedy was quoted by NBC News as saying.

No injuries were reported in the fire-fighter pullout. However, the fire crews have been unable to assess damage around the lake due to downed trees and necessary clean-up, McCreedy said.

Apart from that, authorities evacuated 159 houses on Monday, according to the National Wildfire Coordinating Group. The group, however, said that cabins, homes, and recreational sites remain under threat from the fire.

According to the fire officials, the fire in and north of Superior National Forest has mostly gone according to the weather. It was expanding on Monday due to the dry fuel on the ground and temperatures in the high 80s.

"The winds were drawn into the fire from all directions. It created what we call pyro cumulous clouds. And really high in the atmosphere, you would see a thunderstorm, and in fact, they went high enough to produce a few sprinkles of rain and even some lightning," the incident's fire behaviour analyst Michael Locke, said on Tuesday.

Experts believe that the extreme weather has been set in by the climate change, including an increase in the frequency and intensity of wildfires in the Northern Hemisphere.