Should be noted that in Norway it is not just for war, but rather any emergency like natural disasters or someone takes out critical infrastructure in a digital attack etc.
You can see all the information that is sent out here: https://www.sikkerhverdag.no/en/
I once again come to inform that "the start of winter" changes depending on where you are.
So in you case that is just how it lines up, but where I live the winter starts October 14th.