Do you have boxwoods close to the foundation? English boxwoods can smell like cat pee to some people.... rain will bring out the scent a bit.

Mold

The exact same smell confused us for a couple years. Turns out we had a buried downspout that was clogged…with rotting squirrel carcasses.

Lots of gutter cleaners don’t do a thorough job with downspouts because doing so can take a lot longer.

You should check for roof/wall leaks. When batt insulation gets wet it smells like cat pee to me. My husband doesn't smell it but I know I do. If the smell is only when it rains I'm guessing you have a small leak and the insulation in your ceiling or walls are getting wet.

Are you on public sewer or septic? Maybe your drain field isn't big enough.

Anonymous wrote:

Anonymous wrote:I second the neighbor's cat. After a heavy rain right by our front door smells like cat urine.

But OP says it’s inside.

Urine in the soil right outside the house can seep through the walls when it rains.