It's all about thermal storage/momentum.
Consider spring and fall equinox. They should be the same temperature, right?
- On March 20, why are the lakes still frozen? Because the hemisphere spent the previous 6 months with the least possible solarization, and the top few feet of topsoil, groundwater, and water bodies are pretty cold.
- On September 23, why is it so warm? Because the hemisphere spent the previous 6 months with the most possible solarization. The planet's surface has been soaking in that heat for 6 months.
So it's really about energy storage in the planet's surface. You probably know if you go to a certain depth, tempertures are consistent all year - but above those depths, the heat (or lack) of prior months affects the surface and atmosphere.
You get a micro-example of this with home heating and A/C.
Half the day's solarization happens before noon. (1 PM daylight savings). So why doesn't it start getting miserably hot in the summer until 2-3 PM (and/or that's when the A/C system really starts working in earnest)? It's our buddy thermal momentum/storage again. This time, in the structure of your house. It takes hours for solarization to warm the exterior of the house against the prior night's cooldown, and then hours for that heat to soak through insulation.
Now why doesn't that A/C just run when the sun is strongest from 7 AM to 5 PM? Because we're using ancient designs that presume fossil fuel and hydro power, and focus on comfort - aiming for 23°C/73°F at all times. Solarization accounts for the lion's share of need to run A/C, so this time delay in "solarization vs. A/C need" is a huge grid management problem, called the "Duck Curve". Smarter people would realize the value of the thermal mass inside the house's insulation envelope... and have the A/C run when advantageous, e.g. exactly when the sun shines. If everyone did that, the Duck Curve would go away.