peppers and tomatoes need a range of daily temperatures to pollinate.
the plants proper love the full sun and heat (given TLC water, etc) but if the temperature stays above x'F "all the time" they will not pollinate - which means,,,, no fruits.
of course, if it's too cool, they won't pollinate either. just to keep the record "complete"
some years it's just doesn't pay to do peppers. plants thrive, temps stay high, flowers drop, no peppers. then as the season moves on, temperatures are "right" - big plant, blossoms & fruit galore, but now a bit short on sun hours to fuel the plant.
there's a lot of different "numbers" with regard to what's too hot, what's too cool. seems the specific varieties can differ quite a bit, then there's the green/sweet vs "hot" type peppers.
round numbers - daily air temps over 100'F and not dropping below 75'F on a daily basis makes for failed pollination. kindly do not shoot the messenger - the "hard data" is extremely varied and I've not found a "consolidated" source that's made sense of the many reports/studies.
which is all very fascinating, but leaves one with the question:
"it's the weather. what you gonna do about it?"
two years ago - pepper plants did spectacular. got mebbe two peppers.
this year, more better.