Can fog mess with a GPS?

I would say no. You probably drove to an area that has better coverage.

Yes, heavy fog will mess with GPS reception. Water interferes with GPS reception. This is why you wont get reception in the woods either, its not the trees, its all the water in the leaves that blocks it out.

It seems likely that they are related. My parents have had satellite tv for years, and it never works well when there is a significant storm. Since gps units are also based on satellites, it would follow that they would struggle to function during poor weather. Also, since gps units have a much smaller receptor than a satellite dish, I wouldn’t be surprised if it takes less severe weather to disrupt them than it does for the television.

My hand held GPS can never locate satellites on really cloudy days. I have never had the problem with the ones in the cars, but definitely the hand held is affected by low cloud cover.

I’m guessing it would depend on the receiver? My husband works with GPS all over the world and water and cloud cover had better not effect their products… LOL…. but, perhaps those small hand held things or ones in your car have weaker receivers…...Seems pointless to have one if it doesn’t work on cloudy or foggy days.

@cazzie – I’m thinking you’re probably correct. My little hand held cost about $150. I know there are marine hand helds that cost much much more, I am sure you get what you pay for!