Preposition of time : On,In, and At

Prepositions of Time: at, in, on

We use:

• at for a PRECISE TIME
• in for MONTHS, YEARS, CENTURIES and LONG PERIODS
• on for DAYS and DATES

at	in	on
PRECISE TIME	MONTHS, YEARS, CENTURIES and LONG PERIODS	DAYS and DATES
at 3 o'clock	in May	on Sunday
at 10.30am	in summer	on Tuesdays
at noon	in the summer	on 6 March
at dinnertime	in 1990	on 25 Dec. 2010
at bedtime	in the 1990s	on Christmas Day
at sunrise	in the next century	on Independence Day
at sunset	in the Ice Age	on my birthday
at the moment	in the past/future	on New Year's Eve

Look at these examples:

• I have a meeting at 9am.
• The shop closes at midnight.
• Jane went home at lunchtime.
• In England, it often snows in December.
• Do you think we will go to Jupiter in the future?
• There should be a lot of progress in the next century.
• Do you work on Mondays?
• Her birthday is on 20 November.
• Where will you be on New Year's Day?

Notice the use of the preposition of time at in the following standard expressions:

Expression	Example
at night	The stars shine at night.
at the weekend	I don't usually work at the weekend.
at Christmas/Easter	I stay with my family at Christmas.
at the same time	We finished the test at the same time.
at present	He's not home at present. Try later.

Notice the use of the prepositions of time in and on in these common expressions:

in	on
in the morning	on Tuesday morning
in the mornings	on Saturday mornings
in the afternoon(s)	on Sunday afternoons
in the evening(s)	on Monday evening

When we say last, next, every, this we do not also use at, in, on.

• I went to London last June. (not in last June)
• He's coming back next Tuesday. (not on next Tuesday)
• I go home every Easter. (not at every Easter)
• We'll call you this evening. (not in this evening) 

PRECISE TIME MONTHS, YEARS, CENTURIES and LONG PERIODS DAYS and DATES

• at 3 o'clock in May on Sunday
• at 10.30am in summer on Tuesdays
• at noon in the summer on 6 March
• at dinnertime in 1990 on 25 Dec. 2010
• at bedtime in the 1990s on Christmas Day
• at sunrise in the next century on Independence Day
• at sunset in the Ice Age on my birthday
• at the moment in the past/future on New Year's Eve

Look at these examples:

•I have a meeting at 9am.
•The shop closes at midnight.
•Jane went home at lunchtime.
•In England, it often snows in December.
•Do you think we will go to Jupiter in the future?
•There should be a lot of progress in the next century.
•Do you work on Mondays?
•Her birthday is on 20 November.
•Where will you be on New Year's Day?

Notice the use of the preposition of time at in the following standard expressions:

Expression Example

• at night The stars shine at night.
• at the weekend I don't usually work at the weekend.
• at Christmas/Easter I stay with my family at Christmas.
• at the same time We finished the test at the same time.
• at present He's not home at present. Try later.

Notice the use of the prepositions of time in and on in these common expressions:

• in on
• in the morning on Tuesday morning
• in the mornings on Saturday mornings
• in the afternoon(s) on Sunday afternoons
• in the evening(s) on Monday evening

When we say last, next, every, this we do not also use at, in, on.

•I went to London last June. (not in last June)
•He's coming back next Tuesday. (not on next Tuesday)
•I go home every Easter. (not at every Easter)
•We'll call you this evening. (not in this evening)