This is the effect of last season's wet summer on my tomato plants.
It wasn't the cold that caused the blight, it was the rain - day after day - the leaves of plants could barely get dry between showers.
However, on a dryer, happier note, it is not going to happen to my plants this season!
Every outdoor plant is either under a shelter of some kind or can be moved under cover if we get prolonged periods of rain. That's one of the advantages of growing bush tomatoes in large pots etc. is that they can be moved if necessary.
Of course there are blight tolerant varieties available - I use the word tolerant rather than resistant because even these varieties could not cope and went down with blight. The two varieties I'm referring to are Ferline and Legend.
I've sometimes heard people say "the rain will do them good" well, a little drop maybe, but wet leaves for more than a day or two will probably result in the beginnings of what you see in the picture above!