I know that summer in the northern hemisphere begins on the longest day of the year. Summer here in Central Florida, as far as I am concerned, begins when the low temperature for the day is 75 degF (24 C for those of you outside of the US). We hit that point this past week. Our morning low was 74.9 degF, and the dewpoint was right at the same temperature. The high was 92 degF (33 degC) today.
The reason for this, is that the low temperature can’t go any lower than the dew point. At that point, any further energy lost from the atmosphere is spent condensing water vapor, not reducing the temperature. When the dewpoint is at that point, the air starts becoming thick and the afternoon rains begin. If you have ever been in Central Florida during the summer, you know that it rains virtually every afternoon. That’s where we are now. Summer is here.
The dew point temperature is the temperature at which the air can no longer hold all of its water vapor, and some of the water vapor must condense into liquid water. At 100% relative humidity, the dew point temperature and the air temperature are the same, and clouds or fog can begin to form. While relative humidity is a relative measure of how humid it is, the dew point temperature is an absolute measure of how much water vapor is in the air (how humid it is). In very warm, humid conditions, the dew point temperature can reach 75 to 77 degrees F, but rarely exceeds 80 degrees.
Dew point is the best indicator of comfort in a hot climate. Once the dew point of the air exceeds 66 degrees Fahrenheit or so, the air begins to feel hot and uncomfortably stuffy. The reason for this is that your perspiration can not evaporate to cool you off.
![](https://areaocho.com/wp-content/uploads/2021/06/dewpoint.jpg)
The dewpoint here will slowly increase from now until summer breaks in late September. The people who live here know that anything needing to be done outside between May and September is best done before 11 am, when the thermometer typically breaks 90 degF. It isn’t the temperature, it’s the dew point.
Here in Florida, there are 4 seasons:
Hot: March through May
F’ing Hot (Also known as Hurricane season): June through mid September
Still Hot: Mid September through Mid November
Snow Bird: Mid November through February
Beginning in mid June, you get your outside work done in the morning then stay in the air conditioning until at least 4:30 in the afternoon when the afternoon thunderstorms come calling. That is what we do from mid June until about the middle of September.