If you will go between May June ..you will find snow around 500meters before reaching TARSAR.But then it will be a bit difficult for you to trek from tarsar to marsar as almost whole route will be covered with snow but it is not risky you can still go and enjoy trekking in snow.If you want to camp for some nights at tarsar and marsar then visit the place after mid August.If you want to know about base camps and the places you can trek from the base camp of taasar marsar .DM