I too have an old Weather Monitor II (1998 wireless version) and from time to time I have had temperature and relative humidity "glitches". I have taken apart the radiation shield and cleaned the temp/rh sending unit and this has fixed the problem. I live in an area where we have a lot of dust and this fine particulate really gets inside all of the electronics. Just today I performed the biggest "cleaning job" on my station since I got it several years ago. I took apart the Weatherlink module, sprayed contact cleaner on the entire device, took apart the wireless receiving unit and did the same and outside on my transmission "box" (yes it is truly a box on the old WM II units). Thus far, I have received clean data for a couple of hours, and I hope this will fix things for awhile. My CWOP ID number is C2553 in Hanford Ca and you can see by my past data that a major glitch occurred just the other day. Someday I will get a Vantage Pro 2 but for now I am sticking with the old WMII.