I had a similar situation out on the ocean while salmon fishing. It was really foggy and started to rain a little then the thunder started.
The VHF antenna started to buzz. I told my friend I thought the lightning was really close and we should leave.
He started telling me that you can tell when it's getting close because your hair will stand up. I took a closer look at him and sure enough his hair was standing up. Needles to say we headed in.