A load profile is cyclical and highly variable based on region, temperature, season, etc. etc. (mostly region and temperature).
In the south in the summer the load profile is roughly a bell curve peaking at about 5pm. Sun comes up, the earth warms, AC comes on, load is up, 5pm everybody goes home
In the winter, it's a little more complicated, as load comes up in the morning, dips a little during the day, then blips up again around late day, then 5pm everybody goes home.
Spring and Fall? Forget a description - it looks like a wet piece of spaghetti thrown on the wall
So the Summer peak/profile is not the Winter peak/profile and Spring and Fall are something completely different. And for some regions, the winter is the peak and summer is the low load period. So to say there are a lot of variables is indeed a vast understatement.
But for a broad, broad, broad generalization using the South as an example (for discussion purposes only and with all appropriate "unless-its-not" caveats in place), one could say that the baseload (5AM) is roughly 60% of the peak (5PM) on a day where there's a big swing.
Keep in mind that if a couple of clouds blow over, the base/peak ratio gets much tighter.
I have no idea what the Winter profile in a cold northern state looks like. Summer looks like this I think ------------------------------------