I re-hydrated my US-05 at 40C ( 105F ) going by this video https://www.youtube.com/watch?v=SL92Bd4kfbQ. However afterwards I read the on the Fermentis site that it should have been at 27C (+/-3). Apparently it's different depending on the yeast and I should have gone by Fermentis' instructions but would I have done any harm.
It's close, but I think you'll be OK. The commonly cited temp to kill yeast is about 114F. That's a generalization, but hopefully the yeast will survive. FWIW, despite manufacturer's recommendations, I find no difference between rehydrating and not rehydrating. A very experienced friend who runs a homebrew shop advises his customers not to rehydrate due to situations like yours. This experiment adds data to the point that it doesn't matter....http://brulosophy.com/2014/09/15/sprinkled-vs-rehydrated-dry-yeast-exbeeriment-results/
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