Hi luigiwu,
Are they in pots or in ground ?
If in pot, shade the pot at least and check for moisture. If needed put a bigger plate under the pot for them trees to drink during the day.
Here we've been in the 35°c/43°C - 95°F/110°F for two or three weeks (temps in the shade, imagine a full sun position temp at 2PM), and some trees started giving up on older leaves - they are yellowing and will come off .
I couldn't water them as much as would have been needed and that's the result.
3 of my trees looked droopy at some point and I watered them more (40liters/10gallons of water each ) and they perked up.
Those 3 trees are in 80 liters / 20 gallons trashcans buried in the ground for rodent protection ... Well, not the best idea with those temps .
I have an in ground tree that has a yellow leaf and looked droopy yesterday evening - brebas are ripening and might pump all the available water... Still that's just unseen here at this time of the year ... A five years old established tree ... I have some plum root shoots that are now grilled like chicken from the oven.
Hey, you above, Let it rain !!! and let's water more for the ones that can !