In reply to Panda:
I've always sweated loads no matter how fit i've been and at one stage i was quite fit, once, honest !
It won't matter how much you drink. Your body will sweat as much as it needs to to keep your core from over heating until the point that it runs out of liquid and you get very poorly.
It seems to be vastly different from person to person but i can't answer why.It's got to he point where i may have to buy a John Mcenroe style headband as sweat gets in my eyes very badly when climbing in hot conditions.I get the last laugh in Winter when i'm still toasty warm and others around me have turned blue though.
If you were sweating much more than normal for whatever reason your body was having to work very hard to keep you cool. If this is a big change and contnues i'd pop off to my GP.