How long does it take for baking powder to mature in 28 degree weather?

30 minutes to 40 minutes.

Yeast rising has a lot to do with the temperature. It takes about half an hour to 40 minutes for yeast to rise in 28-degree weather. If you want it to rise faster, you can Add some sugar to it. If you want it to rise faster, add some sugar to it. Sugar can promote fermentation.