When the sun is on the top, normally at 12:00 am, the contrast (difference between dark and bright zones) is very different. The cameras don’t “see” the lights like human eyes. Human eyes has more capability to make difference in this kind of situation, this is called dynamic range.
On a cloudy the days, the clouds create and effect similar to a soft box in a flash studio, make the light very soft and the shades disappears, all the scene are in the same quantity of lights. Good, because we don’t have any problem with dynamic range.
Another thing to consider it’s the level of light it could be lower. For this, we must increase the ISO. I prefer to take a photo with some noise that not problems with trepidation (trepidation means when you use a shutter speed not fast enough). Revise the histogram after every photo, and overexpose if it’s necessary.
If you are taking portraits, a small flash it’s a good tool to light your model.
If you are taking landscapes, clouds in the sky make a great composition. Another question, be ready for cold, rain, etc. Be careful to have an accident.
And this is all, thanks for reading.