Not at all!  The harder you work out, the more calories you’ll burn within a given period and thus the more fat you stand to lose. But how much you sweat does not necessarily reflect how hard you’re working. Some people tend to sweat profusely due to heavy body weight, poor conditioning, or heredity. And everyone sweats more in hot, dry weather or dense clothing than in cool, humid weather or porous clothing. (You may feel as if you’re sweating more in humid weather; but that’s because moist air slows the evaporation of sweat.)
Exercising in extremely hot weather or in a plastic “weight loss” suit will indeed make you sweat heavily and lose weight immediately. But that lost weight is almost entirely water; the pounds will return when you replenish your fluids by drinking after the workout. Further, you could develop heat exhaustion if you push yourself too hard in extreme heat or in plastic clothes. which prevent sweat from evaporating and, in turn, cooling you off.