Meditation is to connect to your higher self for the benefit of humanity. It is a conscious practice that empowers you to evolve your God consciousness.
First of all, be in a serene atmosphere during meditation. If the environment in which you meditate is warm, you are likely to sweat during meditation.
However, most people also sweat naturally irrespective of the atmospheric conditions of the environment.
Also, be relaxed and not stressful during meditation. Do the 4-2-4 breath before meditation in order to relax you.
Always remain focused on the meditation. do not be distracted by happenings around you.
Understand that meditation is a spiritual exercised that connects you to your higher self (God.)
Apply all the keys to effective meditation and see a marvellous improvement in your spiritual life.