Hot and Cold stretches

I have a question to others about consistency. As a late adult beginner (moving up the class ranks, currently at C) I have stretches where I'm on fire. This goes from the online tactics server to playing the same folks as always down at the coffee shop to here. There are some days where I'm playing at least 200 points below my normal ability and probably 300 or more below my best chess.

Sometimes I can say "I was tired" or I was moving too quickly. Other times I have no idea why I'm hot or cold.

Others experiences with this?

Yes!!!

I can't explain it either, but I have experienced the same thing.  Sometimes I move too fast, sometimes I react very awkwardly to certain situations.