This may have been covered in the past somewhere but i’m tired and don’t feel like looking through all the posts… 
I am getting a windspeed spike almost every morning and every evening. It appears when there is a long calm period and then a puff of wind. The station records a 20 - 30 MPH gust and then right back to calm. I have ticked the windspike option but it still records and displays it. and clues???
What you describe was a known problem with early versions of the WMR918. OSI replaced the anemometers for free for the folks who complained. The software in the anemometer didn’t debounce a slight reverse rotation that the anemometer made when starting from zero wind and prior to turning in the proper direction. I got my replacement four years ago, and I am not sure if they will still replace broken ones or not. The replacement anemometer did solve the problem.
actualy the windspike in the graph setup i have not implemented with the new graphing…i must do that…
i have the windspeed spike chop in the graph setup working now
(for when yopu get false readings, like from electrical disturbance, etc)
it will be in the next version, 10.17w