I've looked around here a bit, but I haven't managed to find a post that really answers my question (though if there is one, please let me know).
I'm trying to write a story where the two main characters decide to stow away with some travellers who come through their village annually, and I want the travellers to realise that these kids are there when it's too late to turn around and take them back, so the travellers have no choice but to go about their usual annual route before dropping the kids back at the same time next year.
I would like this to be due to some geographical or even season-related reasons and to have the region where the village is located only easily accessible perhaps two or three times a year. So I'm not looking for something like the tides making a certain island only accessible once a day, since that's far too frequent (though it is of course fine if it's a tidal event that somehow only happens a few times a year). Let's also assume that the years and seasons are basically the same as here on Earth.
So, is this possible? And if so, what kind of environment would make it possible for this region to only be easily accessible two or three times a year? (I don't mind if the amount of times the region is accessible in a year is more than two or three, but I'd definitely like it to be no more than four or five, if possible.)
I would also appreciate it if an answer for both how long the region remains accessible (preferably a week or so), and how long it takes for whatever occurs to make the region inaccessible again is given, too.
As a note: It doesn't have to be completely inaccessible for the other parts of the year. Just difficult enough that a band of travellers who are rather slow moving with some carriages and heavy luggage don't think it's worth trying to enter the region outside of those few times a year.
Thanks in advance for any answers given :)
EDIT AFTER CHOOSING AN ANSWER: Thank you everyone who has answered this so far! I have waited about a day and chosen Zxyrra's answer as the best because it's got the most up-votes and for the most part I think it's one of the most useful. Although, there are a number of answers that are similar and I'm thankful to everyone who gave suggestions :)