Hello and welcome!
It really could go either way, the sensor or wiring. The fact that it seems to come back when it rains does somewhat point to a potential wiring or connection issue.
Start by disconnecting the sensor and see if there is any corrosion on the terminals or signs of water ingestion into the connector.
Also take a look at the wiring in the sensor's immediate area and as much of it as you can.
If everything looks visibly ok then you could either opt to try replacing the sensor or do some electrical testing at the time it's acting up to check the sensor's wiring between the sensor and powertrain control module (PCM). Wiring problems are definitely possible and more likely to happen on an older vehicle like this, but the sensor would probably still be more likely.