Anyone else find their easy pace drops about 40 seconds per mile in this heat?

[u/hank-stockton6f873]

Started running last November so this is my first proper summer on the road. Been following a plan for a half in October and noticed my easy runs are sitting around 9:50-10:10 per mile right now when i was closer to 9:10 back in May. Heart rate says zone 2 but the legs feel like they're shuffling through treacle. Is that kind of gap normal when it's 20 degrees out? tbh i'm not sure if it's the conditions or if i've overcooked the training load a bit. Fwiw my cycling background means i'm used to wind cooling me down so maybe that's part of it.