Hot weather/crap performance
It amazes me how much performance is degraded now the hot weather (23c today) is here, you get used to takeoff points, climb out rate and landing distance at your home field then along comes a scorcher of a day with no wind and all of a sudden your thinking " WTF have I lost a mag or left the brakes on" or when landing, I always make every landing a short field, but short final ground speed is noticeably faster and roll out would not win me any prizes at the Alaska STOL contest.
Never thought I was say this but roll on the cold, crisp, clear sub zero winter weather.