Yes, yeast can be safely added in a wash between 20-40°C (68-104°F) maximum.
Above 40°C (104°F), yeast will die very promptly if the wash is not cooled down quickly. This can be done by resting the fermenter in a basin or bath of cold water.
I've added my yeast in a wash at 40°C (104°F), will it still work?
