English prepositions of time in, on, at.

General rules about these prepositions.

We can make some general rules about the prepositions of time: in, on and at. All three words can talk about a period of time when something happened. The time preposition in is used for longer periods of time:

We take a holiday in (the) summer.

My exams are in June.

I left school in 1991.

In the future; in the past; in the 1970s; in the Middle Ages; in the last/next century.

The preposition on often talks about which day something happened:

I'm leaving for Barcelona on Monday.

They went to the pub on Friday evening.

Last year we went to a restaurant on Christmas Day.

On Wednesdays; on Sunday evenings; on my mother's birthday; on Christmas Eve.

The preposition at talks about what time something happened:

Mary gets up at 7.30.

There's a good film on tele tonight at 9.30.

Witches come out at midnight.

At lunch(time); at breakfast time; at dinnertime; at the moment; at sunset; at midday; at the same time.

Festive periods with at.

The preposition at is also used to talk about festive periods when we do not mention the word day:

It often snows here at Christmas.

There is a week's holiday at Easter.

Our relatives come to visit us at Thanksgiving.

Other time expressions with in, on and at.

We usually go away at/on the weekend.

When we generalize about when events happen or mention a specific date/time of an event, we say:

I go to work in the morning(s);

There was a concert in the afternoon(s);

Yesterday, I listened to music in the evening.

But with the word night, we say at night or in the night:

You can hear the owls at night.

The above sentence refers to nighttime or when it is dark outside.

We say in the night when we refer to a time that is very late and most people are asleep:

I heard a strange noise in the night but I stayed in bed.

When not to use time prepositions: in, on, at.

We do not usually use in, on, at with words like next, last, every and this or, if the preposition is possible, it is usually redundant:

I'm going to the cinema next Tuesday (not ~~on next Tuesday~~).

I didn't go to work last week (not ~~in last week~~).

I go jogging every morning (not ~~in every morning~~).

I'm going to see my parents this Christmas (not ~~at this Christmas~~).

Using in to talk about the future.

We use in to talk about events or moments in the future. Often the word time can be added:

Mary will be leaving her job in three weeks (time).

This message will self-destruct in 5 seconds (time).

The world may be a better place in 10 years (time).

Exercises on prepositions of time...

Preposition chart (the most common ones)...