As a Referee, I always have this watch
TEMPERATURE WATCH in my pocket. It's not so good for keeping the 25-second clock, but it's nice to have as a backup if the scoreboard clock fails. It also tells temp and humidity, which is an issue where I work. Of course, if the watch is in your pocket, it tells you the temp and humidity of your pocket. But take it out and swing it around a bit, and it will give you the actual. I always check it before the coaches meeting on warmish days so that when I talk to coaches about heat/humidity concerns, and they say "aw, it ain't that bad today," I know better.