This site is being deprecated.
Please see the official X‑Plane Support page for help.
Check your weather settings and make sure none of the temperature settings are super cold. If that isn't it, move or rename your preferences so you are using the defaults, then send a bug report with screenshots and details on exactly what aircraft / location / etc you were using to see this. If it is a problem with a custom aircraft please include a copy of it.
This site is no longer being actively maintained.