I've seen midsummer defined as anything from late June to early August, but for me it's definitely in July. Last year's cycling midpoint, with a bit of a late start, was somewhere around July 25. Baseball's midpoint, also weather-based, comes this coming Tuesday. School years and rules about white shoes all have summer beginning and ending three or four weeks earlier than the solstice and equinox -- if anything, this year's early spring argues for an earlier definition of summer even than that. All these things point to now, or very soon.
And I have an appropriate plan -- two weeks off for a big, long bike ride.
I set myself an ambitious goal for my cycling season this year. I'm 36% of the way there today. When miss_chance and I get home from our trip, it'll be halfway, just about exactly. That makes the goal still ambitious, since I don't have other long rides planned. But I'm still hoping I can pull it off.