extreme or lacking self-control
intemperate - extreme
The formal word ‘intemperate’ can be used in a couple of different ways, both based on the concept of something extreme. Firstly, if the weather is intemperate, then it is intense and severe. Secondly, if a person is described this way then they display behaviour that is often uncontrolled and characterized by anger and excessive indulgence, particularly with regards to alcohol.
Mike is good in pressure situations because he is level-headed. He never gets provoked into costly intemperate actions.
We had hoped to hold the town festival over the weekend, but the intemperateness of the weather made doing anything outside impossible.
Chris is capable but his lack of maturity is holding him back. He always responds intemperately to any criticism, even if it is constructive.