This was with low 70s. Today I went for a 10 miler and was totally unable to keep MAF rate and so I made it into a threshold run. This means my MAF "runs" this summer are going to feature a whole lot of walking which hasn't happened since January.
So the new plan is, Wake up early (still on lockdown so I don't have to worry about getting ready for a commute) and "run" when it is coolest for most of the week and for faster paced runs I won't worry about time of day. Hopefully this pays off dividends when the temps drop again.