Apart from real perennial classics from bygone times, like

Phew what a Scorcher
as Temperatures Soar into the Nineties

I recall a spoof headline in Private eye, that remains my favourite:

Elderly Horologist Savaged by Heat-crazed Vole

The perfection of this is hard to analyse.

For more, do consult my roundup of the headlines tag. And for a meteorological joke, see here.