Should that happen, Otep, after all we've had lately, it would be wipeout for most butterflies. There simply HAVE to be occasional days where they can go about their business even if conditions aren't perfect.
The problem at the moment is that temperatures are so suppressed that butterflies can only become active in sunny weather, and that has been in very short supply.
I too have seen the long range weather forecast. Whilst we aren't expecting a heatwave, 15-18c, largely sunny with light winds and hardly any rain should be just fine to help the recovery.