In hot dry places, snails often climb up vegetation to escape the searing heat on the ground, and they go into suspended animation, "aestivation" until it rains. Some don't survive, of course. Hibernation is usually underground, or at least under cover, not up plants. - Google
Thank you for your help.
I have read this too and similar, but here ? the ground is covered with gras or plants and the temerature is only 25 degrees max.
Got this off from Quora,
"Here is a bizarre possibility....
Their is a parasite which literally turns snails into shambling zombies.
That is not an exaggeration.
The parasite takes over the brain of the unfortunate snail causing it to do things that greatly increase its chances of getting chomped by some lucky (unlucky?) critter, one of those things is climbing on to the tops of grasses and herbs where they are picked off by birds and the less discriminating grazers like cows, the parasite happily goes along for the ride until it is expelled in the bird/bovine waste.
now there's some food for thought!"