I notice that after parking my car outdoor
even on overcast day at outside temperature
of 65 f, my 2010 outback dashboard gets
very hot. Like it s sensitive to UV, even in not
This is how solar heating works. The glass and the dark dash cover create a lot of heat.
I agree with above stated answer, also without any ventilation such as windows down, fan blowing, ac, etc, the heat just continues to accumulate. Like opening a vehicle's door on a hot day, its usually even hotter inside. This is why you dont leave children or pets unattended inside a vehicle.
That's a normal condition, sun shades help but your car is still going to heat up just due to the sun. Only time this will not happen is if the outside air is cold like 32 degrees so it pulls all the heat out of exposed surfaces.