Yep - get him in a curfew routine. He'll adapt to it very quickly as long as he knows he'll get out during the day sometime. (It would be easier for you in winter, I must admit. Lousy weather and nothing happening out there is a big disincentive compared to the fun at the moment.)
Cats are nocturnal, one of mines stays out all night every night with the exception of snow and the other 2 stay out now and then through the warmer nights, if you want him in at night you will have to keep in him they quickly learn that they won't get out after their meal and disappear before that!