Twelve year old won the San Jose Mercury News weather prediction contest one year, by predicting each day that the weather would be the same as the weather the day before.
Consumer weather prediction isn't about being right. It's about pleasing the customer by appearing to be helpful. Which often means exaggerating the chances of abnormal weather, so if it happens you can be a hero.
Depends, the "optimal" forecast can be very sensitive to the scoring metrics used.
E.g. Darwin in Australia's tropics - persistence forecasting (as you describe above, just predicting the weather the day before) does very well on a metric like 'mean absolute error'. But has no practical skill at forecasting a severe tropical cyclone (aka hurricane/typhoon)! Many are willing to accept some level of false positives and a higher mean absolute error, because the cost of a surprise cyclone is so devestating.
This would work in San Jose because it’s a hot Mediterranean climate. Such climates have very predictable hot dry summers and cool wet winters. In Perth, similar climate, we often go month’s without rain in summer but will have several consecutive days of rain in winter.
I imagine using the previous day would have a much lower skill score in more variable climes.
It was back when I lived in San Jose, during the 1980's. It was in the paper. They had a contest every year, with amateurs trying to beat the weatherman.
Consumer weather prediction isn't about being right. It's about pleasing the customer by appearing to be helpful. Which often means exaggerating the chances of abnormal weather, so if it happens you can be a hero.
Real prediction is boring.