Does heavy rain affect estuary fishing?

Rather a topical question given the weather this last week I'm sure you'll all agree.

I'm just trying to plan my weekends fishing, and was wondering if persistant and heavy rain will affect estuary fishing.

Common sense says that with all that fresh water coming into the river/estaury it should push most of the fish out to sea.

Am I right to assume this?

If thats true, would it also affect the beaches around any estuary perhaps?

Or would it work the other way and with more fresh water, more of a flow of water, then potentially more food for the sea species around the estuary and surrounding beaches?

Your experience and advice will be gratefully received.

Thanks

Mark