The time difference between New York and UTC is -4 hours during Daylight Saving Time (DST) period and -5 hours during standard time period. That is to say, the time difference due to DST is 1 hour. But there are places where the time difference due to DST is 2 hours. They are New York and Sao Paulo. In summer in the Northern Hemisphere, New York is on DST and Sao Paulo is on standard time, so the time difference between two cities is 1 hour. In winter, however, the time difference is 3 hours. This is because DST is in effect in the Southern Hemisphere while the Northern Hemisphere is in winter. Therefore you need to pay special attention to this point when traveling or making call between the Northern and the Southern Hemisphere.