The effect of light, temperature and rainfall on bud fruitfulness of six grape varieties were studied in Pune, Nashik, Sangli and Solapur regions of Maharashtra. The potential bud fertility in Thompson Seedless, studied at Research farm of Maharashtra Rajya Draksha Bagaitdar Sangh, Pune revealed that the basal three nodes tends to be less fertile. The highest fruitfulness, ranging from 59 to 76 per cent was noticed on the bud position from 5 to 9 and decline at both ends. The fruitfulness of bud of different grape varieties revealed that it varies widely from region to region and among different grape varieties. The variation between the grape varieties in different regions, in the way of their fruitfulness responded the climatic conditions during bud differentiation stage. In Pune, Nashik and Sangli regions, the climatic conditions of high temperature and high light intensity favored for high fruitfulness in all varieties. In Solapur region due to high rainfall & low light intensity, the fruitfulness affected severely.