Tomato fruit will not set until nighttime temperature is above 55oF for at least 2 nights in a row.
It is difficult for me to discuss in English. I understand the University of Florida sharing that the temperature will not rise above 55 ° C for longer time at night. And that was in my hot spot. It can be seen from the measurement chart that ten to twelve hours a day was below 55 ° C in the hot spot. The shorter time was only in the night of 3.4. on 4.4.
That the temperatures at night fall below 55 ° C in May (even several consecutive nights) and the plants set the fruit is nothing unusual. But the text from the University of Florida is not written:
Fruits are not set if night temperature drops below 55 ° F.
I don't know if I wrote it clearly.
Vladimír