 More sensitive people may feel the need to put on long sleeves and a jacket come evening Friday. However, a quick turnaround, people. You'll go to sleep with the windows open Friday night, wake up Saturday morning, and notice the air has turned muggy once again. From New York City on south and west, warmth and humidity will quickly build across that region on Saturday. As the air becomes more humid, spotty showers and thunderstorms are likely to erupt.