Smoke from Canadian wildfires​ is headed toward Massachusetts, and prompting concerns about air quality in Boston.

“Most of the time, the smoke will be high-flying and dim the sun, leading to vivid sunrises and sunsets and causing a hazy appearance to the sky overhead,” AccuWeather Meteorologist Brandon Buckingham said.

An air quality alert is in effect for some parts of Massachusetts on Thursday as temperatures hit the 90s — and thunderstorms are on the radar. Here's when and where the rain is supposed to start.