Hello, EmanyB. Are you on a long acting ( basal) with short acting (bolus) for meals regime? If so, you need to ask yourself the question, 'did I still have active k sulking from a mealtime Bolus on board?' If the answer is yes, then you didn't eat enough carb to cover the insulin. If no, then maybe your basal needs adjusting. Everyone's insulin requirements are going a bit peculiar in the hot weather, you need to work out if you are one of those whose insulin works extra well so you need to reduce it, or if you're one who needs more insulin to mop up he extra glucose your liver is pumping out becaus your body is under stress. It can go either way!
If you are on a mixed insulin, that's a tougher nut to crack, you have to make sure you are eating enough regularly to match the insulin, or another way round, not giving yourself too much insulin so that there's too much of it for the food you want to eat.