I think it's the perception that the temperatures are now super duper hot, so red. When five years before they were just deemed normal, and so green. Global warming and that.
Oh right I just thought it was a change in the graphics but yeah I suppose there's a lot of hype like that going on. Storm names and stuff like that.
I was thinking this the other day, I always knew America named it storms, but I thought when did we start naming storms....it appears from a quick google it was 2015.
I suspect if 37 degrees was green, green didn't mean normal, they just didn't use colours. That said, 22C being "red" or "hot" amuses me.
Storms are named in alphabetical order for each year, that way you know how many storms you've had - the names I read are those of people who work in meteorology etc, well for the UK anyway - it's nowt to do with how severe they might be.