I can only tell you how we handle such things in our PnP Group.
In our group, the rule of thumb is: If you forget a critical fact and suffer for it, it sucks to be you, but we will not roll back. This has, however, only happened once to date, because the GM always had the decency to give hints in his explanations.
In your example: Don't say "You are entering the water, what do you want to do?", but say "you are entering the water. Immediately, you feel your legs go numb from the cold.". Remind the player of the things he might have forgotten during the descriptions.
Now, since you are not the GM in this case, I know this doesn't really help you. I would definitly have a word with my GM if this was to happen in my group, tell him how I feel about it. Especially if it's something really simple like the aforementioned description that the water is cold, it's really not too hard and in fact adds to the atmosphere, in my opinion.
This changes if the players forget a vital clue in a crime story or something like that. In that case, I (as the GM at that time) left the players in the dark about it (As they were taking notes, but just forgot to note this special thing down, so it's really not my fault when they forget something). But as I saw that there was no chance that they would remember on their own, I nudged them back towards the person they got the information from. At that point, one of the players remembered the clue, and I did not need to use an NPC to point it out again. This only works if the clue was given during the same evening or a few days before, not if you are only playing every few months.
Which brings me to the last point: In my opinion, if you are playing once every few months, the GM should go easier on the players memory (Especially if they lost their notes). For me, it's always the better choice to have some NPC give them the clues again instead of letting them in the dark and completely killing the flow of the game. Nothing is worse than players who are frustrated with their GM.
This answer focussed a lot on the GM side, because I think that these things should ultimately be decided by the GM. But it doesn't hurt to talk to the group as the GM, and it especially doesn't hurt to talk to the GM as a player. The GM will most likely not know that you are frustrated with his methods, unless you tell him. And if he's a good GM, he will take it as constructive criticism and not as a personal attack on him (Almost happened to me once).