Ahh, found it. I was using an app initially but realize what you were saying once I launched my browser. Yes, it seems to be a mistake but you can change the number to 31.2 by adding a period to the number right there as just did. I agree that the default value is not correct.
Environment Canada provides astronomy forecasts https://weather.gc.ca/astro/index_e.html - I am not sure they do anything more than a North American model, or if anyone else provides anything similar. I use their cloudiness, transparency, and seeing forecast maps all the time through http://www.cleardarksky.com - Clear Dark Sky also models darkness relative to sunset/sunrise and moon brightness.