May sounds like a silly idea, but wih this hot weather, it could be that you are more dehydrated than usual.
The body often mistakes thirst for hunger, so the feeling hungry, could be your body saying it is thirsty. Then because you are eating instead of drinking, you stay thirsty, which your body reads as still hungry.
Irritability, tiredness and lack of concentration are very very common symptoms of dehydration. I suffer from this alot when i dont drink enough.
Next time you are feeling hungry, or before a meal, have a couple of glasses of water about 15/20 minutes before you actually eat. It should help you want to eat less at meal times, and it can also make thirst related snack attacks disappear.
Hope you feel top form soon.