For crowd purposes I would go in February. Besides August is super crowded. I love going to the parks when they aren't busy! I don't know any of the refurb dates for Matterhorn but HM should be up around then.
When you day August is crowded do you mean just weekends because we go on the weekdays about the second week in August and its pretty good. Most wait times are under 20 min besides Space, Splash, and sometimes Indy
Disneyland emailed me back and said that they do not have a date set yet for the refurb of The Matterhorn. So I guess we just have to make a guess. I would think August would be better for all rides being open but February would be better for wait times and weather.
How hot is it typically in mid-late August at Disneyland?