No doubt it’s summer month in Kashmir where temperature doesn’t cross 25. An ideal time to visit Kashmir, where night might turn cold. so it’s better to carry one or two winter clothes in hand.
You can take one sweater and jacket with you as at night the weather is cold. As you will be visiting Gulmarg and that too 2nd phase so there would be snow, so you would need a jacket and sweater for that. A good warmer is enough..