A. During and For
During says when something happens; for says how long it lasts.
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
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.)