I also think that at lower temperatures the sweetness will be bigger. Meanwhile, we have 26-31 ° C in the full two months and over 15 ° C at night, only one week in June was cooling. These temperatures are 5 ° C higher than normal and are not good for Czech tomatoes as well. The only tomatoes that are good for me today are Spanish steaks. Probably because in our country the weather like in Spain.
Vladimír