Two different streams of research have found the same conclusion. When it is hot, your aggression goes up, but not in general. Mostly it is the revenge component that goes up.
One of the studies looked at baseball. The chance of a pitcher retaliating for hit batsmen is much higher in 95 degree weather than 55 degree weather.
The other study looked at indoor environments. People were more likely to view others’ actions as hostile and it lowered the threshold at which people took revenge for the hostile action.
The benefit of the baseball study is that it isolates all of the other cultural variables that interact with perceptions and actions. The benefit of the second study was that it is more ecologically valid (more like our real lives).
So if you are managing a hot workplace, whether it’s outdoors or just near hot machines and processes, this is something you have to worry about. Try to keep the temperature below the 90s. And if you can’t, take some preliminary actions to prevent revenge and hostility. That can really destroy workplace morale and productivity.