A shroud of smoke has sent solar power generation in parts of the eastern US plummeting by more than 50% as wildfires rage in Canada.

Solar farms powering New England were producing 56% less energy at times of peak demand compared with the week before, according to the region’s grid operator. Electricity generated by solar across the territory serviced by PJM Interconnection LLC, which spans Illinois to North Carolina, was down about 25% from the previous week.

Massive wildfires are more commonly associated with the US West, but drought across eastern and central Canada has sparked thousands of blazes there so far this year, blanketing the US East Coast and Midwest in an orange haze. As climate change spurs hotter, drier conditions and solar becomes a bigger part of the power mix, grid operators will need to prepare.

Read more: A Third of California’s Solar Power Can Vanish Because of Smoke

“With a situation like this, it’s really unprecedented” in the Northeast, said Matt Kakley, a spokesperson for ISO-New England. “We don’t have a lot of historical data to look back on. There is some learning in real time.” Solar accounts for about 3% of power generation in New England.