I mind one time... July 4 in the mid 80s... I was camped next to the Nepisiguit at Popple Depot and there was a thick frost. Another time, August 10. The Nepisiguit runs out of some fairly big Appalachians and is spring fed nearby so the fishing was good. There is a wardens' camp opposite the (then) primative 'campgound'. I used to get up at dawn and catch trout for brekky, wait until the wardens went up the road to do some wardening and get back to fishing. I could only stay in the river 15 to 20 minutes as my legs would be so numb that it was hard to walk. By noon, it would be so hot that skeeters couldn't fly.