If you have weather feature active for your account, you can see the weather as it has happened in your Gantt as well as project report. You need to make sure you have added the address of the project in project settings.
Gantt:
Project Report:
Legend for the colors in Gantt:
Yellow - sunny
Grey - cloudy
Light blue - light rain/snow/sleet
Blue - rain/snow/sleet
Dark blue - heavy rain/snow/sleet
Blue-ish White - fog
The same as background - no data for that date