DURING is used to say WHEN something happens; FOR is used to say HOW LONG it lasts. Compare:
 
- My father was in hospital during the summer
- My father was in hospital for six weeks
 
- it rained during the night for three hours
- I can see you for a few minutes during the afternoon
 
In many situations (but not always), we can use IN instead of DURING:
- I woke up during the night = I woke up in the night

Hay que tener cuidado porque en español "durante" significa normalmente "for", no "during", y además suele omitirse. En los ejemplos anteriores, si suprimimos la palabra "durante" de las traducciones españolas queda mejor:
- mi padre estuvo ingresado seis semanas
- llovió tres horas por la noche
- puedo verte unos minutos por la tarde