Voted for
- 19-21 °C
If I've done the math right, somewhere between 19-21 C is good. If it's a tad on the chilly side for some reason, a light jacket of some kind or a heavier shirt maybe. Too much above 21 and I'm probably reaching for the thermostat to turn on the air conditioning.
We've had a couple of high temperature days (for us in June), too. We had 95 degree F weather for two days, but now it's cooled back down to the mid-70s. It bumps back up into the 80s next week, which again, is early for us.