During the summer months, it is common for temperatures to reach over 90 °F (32 °C), with an average of 106.5 days per year, including a majority from June to September, with a high of 90 °F or above and 4.6 days at or over 100 °F (38 °C). However, <answer>humidity</answer> usually yields a higher heat index. Summer mornings average over 90 percent relative <answer>humidity</answer>. Winds are often light in the summer and offer little relief, except in the far southeastern outskirts near the Gulf coast and Galveston. To cope with the strong <answer>humidity</answer> and heat, people use air conditioning in nearly every vehicle and building. In 1980, Houston was described as the "most air-conditioned place on earth". Officially, the hottest temperature ever recorded in Houston is 109 °F (43 °C), which was reached both on September 4, 2000 and August 28, 2011.
What weather factor produces a higher heat index?
humidity