From Merriam-Webster's online dictionary comes the following clarification [my emphasis]:
Effect and affect are often confused because of their similar spelling and pronunciation. The verb 2affect usually has to do with pretense "she affected a cheery disposition despite feeling down". The more common 3affect denotes having an effect or influence "the weather affected everyone's mood". The verb effect goes beyond mere influence; it refers to actual achievement of a final result "The new administration hopes to effect a peace settlement". The uncommon noun affect, which has a meaning relating to psychology, is also sometimes mistakenly used for the very common effect. In ordinary use, the noun you will want is effect "waiting for the new law to take effect" "the weather had an effect on everyone's mood".