You're probably mistaking a thunderstorm for minor precip. Air traffic control wouldn't let anyone on VFR take off or land on an airport when there are major T-storms.
Edit: Oh, were you riding the airlines? (Derp.) They might TAKE OFF through a rainshower or a minor T-storm if the weather at their destination is fine, but only because they can climb out of it quick. But there's no way an approach controller would give you vectors for an ILS if it was through a T-storm even I'd you had filed IFR.