I shouldn’t have to explain this but conservatively shade vs non shade is about -10/+10 in terms of real temperature.
That’s point 1
point 2 is key — this matters in how many south facing windows you have, but if you maximize that, the heat captured is incredible as the lower angle is directed into the core of the house rather than to the roof as in summer. This affect is not well correlated to atmospheric temperatures…
Next time you go into your full-sun exposed car, and it’s 30-40 outside take note how it’s 65+ in your car. That heat is captured and not irradiated back. Same as your home. If you’re paying attention, these are basic physical processes at work and intuitive.