Right at day 17 too! Better get a third one before lock up and hope for the best! This humidity thing is tricky....
You could calibrate them so, you know if you need to add to or subtract and how much from what it's reading. You still have time before lock-down. Here's a link with info. https://www.backyardchickens.com/t/115856/calibrating-hygrometer
It's super easy to do a salt test to calibrate your hygrometer. If your hygrometers are adjustable then adjust them to read accurately after the test or simply put a piece of tape to tell you to add or subtract whatever the amount it reads off from calibration. Items needed: small bottle cap zip lock type bag 1 or 2 table salt water Put salt in bottle cap, add drops of water until damp not sloppy or making a slurry just damp paste consistency. Put cap and hygrometer in zip lock bag (allow air in bag for bubble) and if want to put that bag in another zip lock sandwich bag. Wait 4 hours with this on your table. It should read 75% humidity if not then that is how much your hygrometer is reading off true RH. If your hygrometer is adjustable wait to adjust until it settles back down to room humidity. It drops so fast you'll never do a proper adjustment until the gauge stabilizes back to room RH.
