Here are a few suggestions that came to mind.
1. Add annual precipitation anomaly.
2. Add an option to export weather parameters from selected points and cities to CSV.
3. Add fire risk.
4. Add observations from weather stations being displayed on the map.
5. Add 16-day ECMWF forecast.
6. Add new snowfall to past days, currently it is only available for future days.
7. You could add snow depth maps for at least a few years farther to the past as currently, as I have not found a global map for this, only a few regional maps. I consider snow depth a more important parameter than precipitation and wind speed. Also, you could add pressure systems and weather fronts to all maps up to 1979.
8. Add an option to display temperatures in Kelvin.
9. Add Canadian Air Quality Health Index.
10. Add day/night map, customizable by time zone.
11. Add snow depth, pressure, humidity and UV to meteogram.