A solar flare just wiped out your power.

[CucumberedPickle]

message body needs filling.

[Hans Lemurson]

Heat wave.  Although both can be survived with a sufficient stockpile of wood for campfires/coolers, heat will make your food spoil and Dusters give much less thermal protection than Parkas.

On the other hand, heat will not kill your crops like frost will, but that's not something a Solar Flare would impact unless you're growing temperature-controlled food indoors.  And even then indoor farming is often done in hydroponics, so your plants are likely to die in any case.

[Canute]

People which set their defence mostly on turrets will hurt a Solar flare when it happen during a raid or when a raid happen during a flare.
But beside that a flare is pretty harmless but annoying. Except you settle on some extreme biome and you don't have any backup for cooling/heating.