Rain blows in stove exhaust fan flap when closed!?

Self adhesive weatherstripping.

Ok..thanks...

How about a tiny strip of masking tape or duct tape on the flapper where the tab rests?

Are you going out and purposefully locking the tabs when it looks like rain? If so I might try just a strip of masking tape covering the entire opening.

If you're storing it you might get a chunk of closed cell foam (the kind that doesn't work like a sponge Cut the foam to shape an dwedge it in the hole under the hood to press the flap closed.

Clothes pin is what we use. Just clip on plastic thing in middle. But maybe I have a different model?

If you are talking the exhaust range cover Im wondering if the seal on top is broken and letting water in as the flap is covered and would really have to be a driving rain to push it up in there. Over the years I have had a few leaks on our old camper that sits outside at the lake year round. I was getting drips when it rained right above our bed (24'TT BH)Thought it was the window leaking turns on it was the window frame a little lap seal on the top and sides and leak was fixed.I got clear sealant and went over all the window tops and vent covers as the old stuff had dried and cracked,good luck hope this helps.

You do have a vent cover over that flap don't you?

To the OP etc,

Without an actual pic of your outside vent or a link to it in an RV parts catalog or something like that, it nearly imposible to give you much real help. Even the year and model of your RV may enable a member to look it up and know what your outside vent looks like. Most RV's have a cover at an angle which covers nearly the entire flapper area and fends off rain but some RV manufactures simply used the exposed flapper to somewhat protect the outside vent and yes, they do leak in a rain and let air blow in or heat being sucked out too.

We have never gotten as much as a drop of rain come in thru any of our many RV thru the range vent or air either and all had the angled flap cover. For winter, we slide or snap the screen off that's on the top inside of the range hood and put a plastic storage bag over the screen and fold the excess on the back side and tape it there so the range side is smooth and invisible. Then slide or snap the screen back on. Of course, the outside flapper lock tabs are also nolding the flapper closed. Then when using the range to cook, just open a ceiling 14" X 14" hatch cover a little and out goes the smells and humidity and then close it. We can't stand that constant flapper snapping open and closed noise when the wind is blowing so ours are normally locked in the closed position and use the ceiling vent even in spring, summer, and fall. They're about useless as far as we're concerned.

Stove vent cover should look something like this

or this

Are you missing the outside wedge cover?
If they are there, maybe a bit of sealant around the top is needed?

If you have a Jensen vent that looks like the picture below, the rain can come in behind the swing up cover and come in behind the flap. That black weatherstrip accross the top should keep out the rain but can get compressed and need to be replaced.

the first pic is what we have...the caulk around it is all good...the rv is parked on waterfront, east end of Lake Ontario, where we do get high winds and driving rain at times...today i wedged a piece of white packing styrofoam in between the flap and cover, maybe that will help...thanks for the ideas