Would it be feasible to implement a rudimentary weather sim in game and have it interactive?

By interactive I mean that the wind and rain affects gameplay. You can fly up and through the clouds.

You can be randomly struck by lightning.

Or maybe in a sandbox type or RTS game, player actions such as industry or heavy resource harvesting could affect weather.

Sounds like a good idea or perhaps just a gimmick?

Roller Coaster Tycoon I already had this.

Guests didn't like the rain, and would avoid open rides, and buy an umbrella.

As another example, in Final Fantasy XI weather affects magic damage, and certain enemies only spawn in specific weather conditions.

Lots of games use a reasonably detailed simulation for weather to feed back into the game mechanics. Hearts of Iron 3 for example has weather potentially playing a huge part in combat due to the modifiers it generates.

So yes, weather can have a very useful and interesting impact on a game. It is up to the designer to decide how it should work, and needs to be evaluated as to whether the results are interesting or annoying. Of course, this goes for any element in game design.

Wander gathers historic weather data from a specific location in the real world, and streams that data into the game world to create a believable virtual climate. Rain / wind / temperature have a big impact on the flight mechanics (based on paragliding) IIRC.

Caveman 1.0 and 3.0 both feature complete weather modeling, including water tables and flooding. anger the gods, they send the atmospheric pressure into a nosedive, the weather engine takes over, you get torrential rains, and the flood waters can actually sweep your character away!

weather also affects mood, exposure, caloric usage, puts out fire, wakes people up when sleeping out of doors, etc.

temperature effect on food spoilage is on the todo list.

Weather can affect things in fairly broad ways - bullets dont fly straight in windy situation, rain loosen the tension of bowstrings, rain/snow obscures visibility and effects endurance/encumrbance for movement.

These largely can be implemented with weather varying effectiveness factor for various action.

Same can be said for nighttime situationals.

By interactive I mean that the wind and rain affects gameplay. You can fly up and through the clouds.

Legend of Zelda:The Windwaker had this and i bet most games where the protagonist can fly have wind-effect,

these games or levels are build around these (fun) mechanics.

Sounds like a good idea or perhaps just a gimmick?

Gimmick.

You can turn it into a good idea, but you'll have to work hard at it.

weather can be a big part of flight simulation.

a lot depends on the game. for a casual game, weather will most likely be just a gimmick. but then again, almost everything in a casual game is just a gimmick, so....

basically, the more realistic the game, the more weather becomes a game play feature, and less a gimmick. weather is some SERIOUS sh*t in silent hunter 5. in the sims2 for the nintendo DS, its just an alternate ground texture set.