A. During and For

During says when something happens; for says how long it lasts.

Compare:

My father was in hospital during the summer.

My father was in hospital for six weeks. (NOT . . . during six weeks)

It rained during the night for two or three hours.

I’ll call/in and see you for a few minutes during the afternoon.

B. During and In

1 We use both during and in to say that something happens inside a particular period of time.

We’ll be on holiday during/in August.

I woke up during/in the

night.

2 We prefer during when we stress that we are talking about the whole of the period.

The shop’s closed during the whole of August.

(NOT .. . in the whole of August.)

3 We use during, not in, when we say that something happens between the beginning and end of an activity (not a period of time).

He had some strange experiences during his military service.(NOT . . . in his military service.)

I’ll try to phone you during the meeting. (NOT .. . in the meeting.)