I'm not sure what my upper limit is for temperature yet. I've ridden a lot in the mid 80*f with relatively high humidity. My only complaint so far about riding in hotter temps is when sweat gets in my eyes. I've the gutter headband thing and didn't like that. Recently I've been wearing headsweat beanies that seem to work well so far. I won't usually ride below 40*f unless it's a really nice day.