A hailstorm causes wildfires?
You learn something new every day.
Well, many giant blocks of ice streaking down to earth at unimaginable speed resulted in something quite different from what you see in typical hailstorm. The release of heat from such collusion is so vast that it will instantly vaporize comet and set everything in its neighborhooed on fire.
It was all that nuclear bomb energy released that caused the fires...but somehow didn't prevent the freezing.
Everything lined up just exactly wrong, allowing Heisenburg's uncertain little demon to make everything colder, the hotter it became, just like putting a tea kettle on the fire to freeze, or into the fridge to boil.
That occurred to me, too. From the context is appears (but how can you be sure?) that he means a hail of meteorites.