Do you known when is the warmest time of day? Is it noon? Nope! How about the coolest time of the day? Is it 3 a.m.? Nope! The following is general information, and cold and warm fronts can change temperatures out of the general norm.
Heating is cumulative throughout the day, thus the maximum temperature usually occurs around the middle of the afternoon. At this point in the day, the sun is still high enough in the sky to continue to warm the surface and with the addition of the solar energy that has accumulated up to that point.
The coolest part of the day is about 30 minutes after sunrise. This is because cooling overnight is cumulative. With no solar radiation, the temperature cools during the night and is not able to recover until the sun rises and gets high enough in the sky to start warming the surface.
Below is an example from Professor Cliff Mass from the University of Washington.
Just for fun, what day is the coldest day in winter? The answer is, it depends! It’s hard for a meteorologist to be definitive!
Below you can see when the coldest day of the years is across the United States (from the National Centers for Environmental Information). The coldest days of the year in our area are generally from Dec. 22 through Jan. 4, per the National Weather Service office in Albuquerque.