I've always been taught to say AT the weekend, not ON the weekend, but recently I've come across the following sentence: Clifton's very crowded ON the weekend.
It makes me wonder where native speakers in the UK or the USA use this preposition in this expression/phrase.
Because I've mentioned a post on Language Log, A weekend is not a surface, I think I should write about it a little, boiling it down to a short, useful post.
Though this question is only about on or at (the weekend), the post on Language Log summarizes it nicely:
An attempt ensued to achieve descriptive accuracy. It was agreed that times within the day generally take at (at 9:30, at noon, at dawn, at dinner, at night), except for those that take in with the definite article (in the morning, in the evening); that days generally take on (on Monday, on her birthday, on Valentine's Day), except maybe for at Christmas; that months and seasons and years and centuries generally take in (in December, in winter, in 1893, in the 15th century). And never mind the (generally relative) time-references that don't take any preposition at all, like tomorrow, next week, three days ago.
That's really useful, not just because it covers all the most common prepositions used with time expressions (at, on, in); it also hints at how we can conceptualize these expressions so we can use them appropriately.
The next paragraph also gives a big clue to the difference between dialects:
This all hints at a coherent metaphor: hours and other short periods of time are places; days are surfaces; months and longer time periods are containers. But it seems that only North Americans apply this logic to weekends.
So, it's rather clear that only North American speakers will normally use on with weekends. On (not at or in) the other side of the pond, it seems like at is the choice.
That's as far as I can go. Beyond that, you have to rely on yourself (the mentioned Martin Haspelmath, "From Space to Time: Temporal Adverbials in the World’s Languages", 1997, seems like a great read). I also hope more native speakers will chime in soon.
Applying the preposition "at" to a time suggests that the time in question should be regarded as a single moment, while "in" or "on" implies that it is an interval. Most nouns referring to times are either used mostly to refer to moments, or used mostly to refer to intervals. Sometimes, however, nouns which are usually used to refer to moments can be used as intervals, or vice versa. Consider the difference between:
The cannon will fire at sunset.
The cannon will fire during the sunset.
Although "sunset" is normally used to refer to an instant in time, it may be used as in the second example above to refer to an interval (most likely the interval between the time the sun touches the horizon and the time it is completely obscured, though perhaps extending somewhat beyond).
With regard to "the weekend", I would suggest that it is usually used to refer to an interval, and in most cases where a moment would be required common usage would substitute "the end of the [adjective] week" (e.g. "work week", "calendar week", etc.) so as to make clear the exact moment being identified, or perhaps "at the week end" or "at week's end". The phrase "at the weekend" would only make sense if "the weekend" started as some well-defined moment. It's possible for formulate examples that would make sense in business contexts (e.g. an interval might be described as starting "at the weekend" if it starts at the close of business on the last business day prior to Saturday) but in most cases it would be unclear what exact moment was supposed to be described.
