Prepositions of time: at, in, on.

Use at with times of day, including mealtimes, bedtime, etc.

at 3 o’clock, at 10.30am, at noon, at dinnertime, at bedtime, at sunrise, at sunset, at the moment

Use in with months, seasons, years, decades, centuries and long periods of time in general

in May, in the summer, in 1990, in the 1990s, in the 20th century, in the Ice Age, in the past/future

Use on followed by days and dates

on Sunday, on Tuesday mornings, on 6 March, on 25 December 2010, on Christmas Day, on Independence Day, on my birthday, on New Year’s Eve

Also, use at in the following common expressions

• 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/at the moment: He’s not home at present. Try later.

Parts of the day

• in the morning
• in the afternoon
• in the evening
• at night

last, next , every and this

When we say last, next, every, this we do not 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)