A few years back my family was visiting Niagara Falls, Canada on a hot September day. Suddenly the sky became extremely dark and it was obvious that a storm was approaching. I left my family, including my mother-in-law in a wheelchair, at the bottom of Clifton Hill and ran back about half a mile to where I had parked the van,.As I started to drive back to pick them up the storm hit. It started to hail, first small pellets, then increasingly large until they seemed to be the size of golfballs or bigger. I pulled up under a tree and actually got in the back because I was afraid the glass would break. When it eased off and I reached the bottom of Clifton Hill, my family were standing in over a foot of freezing water with giant hail stones floating in the mix. My mother-in-law was freezing and my father-in-law had actually climbed the wall to stand on the edge of the Niagara river - not normally a good move!
As we fled the area, we stopped briefly to video the giant hailstones on a lawn - wish I could find it now! Once we got back into the sun again it seemed surreal that we had gone through such a terrifying, but very localised, experience. My daughter dreads going back to Niagara Falls even to this day!
Postscript: That night I heard on the news that some house windows were broken in the storm. And, it cost $2,200 to repair the dents in the van!