It actually hasn't been this year, that is part of the problem. We had a two week time frame where the temp was below 25, during the day. I grew up in the midwest and it still seemed cold to me. Last year it snowed five times, iced twice. It was colder last year here in Olympia than it was in my hometown of GAlesburg, Illinois.
He is dedicated and he goes out and throws but I don't expect him to hit the cage (we have a 70 foot cage in the backyard) and throw when it is below freezing. Likewise if there is snow (we had snow and ice on the ground for over a week before it melted last year) on the ground I don't have him throw.
The climate is changing. It may be warmer other places but it isn't here.