I’ve run the marathon here twice - 2019 and 2021.
I ran the half this year and did indeed PR, but my half PR is weak as I don’t run them often so that would have happened regardless of conditions. I don’t think the weather was substantially better than 2019 or even really last year.
The thing with Grandmas is while you can have cool weather and a tail wind, the sun does play a factor.
Less so in the half marathon as that starts just after sun rise at 6am so about half of old highway 61 that the race course runs on is shaded by the trees between the lake and the highway as the sun rises. But you are still very exposed for the about the last half of the race.
By the time the marathon kicks off 90 minutes or so after the half the sun is already higher and the amount of shade is far less in the early portions of the race and pretty much full exposure the last 10K or so.
If you don’t handle the sun well you may struggle regardless of temp and tail wind.
Keep in mind this is a race that runs within days of the summer solstice when the thermal energy is at its highest. This is not an April or October marathon.
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