Another climate element that makes Guilan prominent among other provinces is the relative humidity. Relative humidity is generally the highest in the early hours of the morning and the lowest in the middle of the day, as it is calculated based on the ability of the air to hold moisture at different temperatures. Colder air can potentially hold less moisture and warmer air is more likely to hold moisture. For example, even if the absolute humidity in the air does not change in the morning and at noon, because the temperature is low in the morning and at noon, the ratio of absolute humidity to low and high temperatures will vary at different times. Day and night, it increases its proportion in cold weather and reduces it in hot weather. However, although relative humidity is generally high in the morning, and low in the afternoon, it is still harder to tolerate midday in the warm seasons of the year because of the humidity. It is higher, so that the 30-year average of the two times of day and night, 6:30 and 9:30 pm, shows that the center of Gilan (Rasht) with 94 and 72% relative humidity, respectively The aforementioned hours are among the hottest cities in the provincial capitals. After Rasht, Ardabil has the highest humidity with 89% in early morning and Gorgan with 58% in Nimroz.