When I first started running this year I thought “the summer will be great for running!” Now I can’t wait for any other season

It's really what you're used to. When it gets above 21°C here (70°F) in the UK it tends to get very humid and sticky.

Also we're not acclimatised to it. We're currently "enjoying" temps over 27°C (80°F) this week after a much cooler month. This is not typical for September. The nights have been very warm too. I've been getting home after a run the last few days and making a small puddle on the floor tiles.

Looking back, most of my personal best paces have been in the early autumn or spring.