I have not noticed reports for problems with weather info, so this is probably not linked to the software version which will be used by many users. More likely you have either bad incoming data for your local station, or a corrupted setting during the update.
What do you see wrong with the display? Corrupted or missing data? Obviously wrong values? Or ??? (Tell us what you see with your eyes, don't try to interpret). The more detail you provide, the higher the chance someone will get the correct solution first time.
Try switching to the report for a different weather station and see if that appears correctly.
Compare with the weather report on your iPhone.
Make sure you didn't accidentally activate Airplane mode which would prevent real time updates and leave the watch displaying historic data.
Try a forced reset. Press and hold the Digital Crown and Side button (together) for about 10 seconds until the Apple logo appears, then let the watch reboot.