Today we should expect double-glazed windows. The inner pane is supposed to be near room temperature. So ice inside means something is not quite right!

The inside is near room temperature most of the year, but not when it gets down to -20 degrees Fahrenheit (or about -30 Celsius) regularly here. Some amount of ice seems to form on the bottom of the bedroom window any time that the temperature is below around 0 deg F outside.

I did a little research and this seems common in the Upper Midwest climate. R3-rated double-paned windows (which is what I have, I'm pretty sure) can still get pretty cold on the inside when the outside temperature is sub-zero. My heavy blackout shade usage probably further decreases the temperature at the window, since there's no warm airflow across the glass.