I generally do it in the spring. when I change the battery in the FARS. However, I do check the rain cone for crap as well as where wires come into the iSS. Also replace batteries in the fall. I don't want to be trotting out to the station in bad Iowa weather in winter.
I do need to move my soil moisture station back a few feet, that will involve drilling all new holes for the moisture and temperature sensors, through pvc pipe and hooking it up to the transmitter. The sensors need replacing, one is even not reporting. I have on order new sensors from Scaled Instruments. Funny for some reason, these nasty little beatles craw into the moisture transmitter and hide behind the circuit board. Bleah....
this week it is supposed to rain so it might be next week before I can do anything.