Summer Starts

Summer is defined as the warmest season of the year, occurring between spring and autumn. It features the longest daylight hours and the year’s highest temperatures. I also know that summer begins on the summer solstice (around June 21 in the Northern Hemisphere and December 21 in the Southern Hemisphere) and ends on the autumnal equinox. However, I don’t think most of us look at it that way.

It’s the warmth that makes a summer, and in Florida our summers are long, hot, and feature afternoon thunderstorms. For those reasons, I have my own definition of the beginning of summer. Here is Sector Ocho, summer is the first day of the year where the temperature doesn’t go below 75 degrees Fahrenheit (that’s 24c to those of you in countries using the metric system).

I have a personal weather station in my backyard that I use as my official measuring station because I don’t believe Florida’s numbers. My weather station is one of these. It’s located in my backyard in the middle of a clearing with the nearest block to wind (a tree) being at least 50 feet away.

Anyway, the first day of summer has arrived, and it was yesterday, May 25. Our low temperature for the day was 75.6 degF. Summer started this year a full 12 days later than it did last year. Our dewpoint right now is 75.8 degF.

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 cannot evaporate to cool you off.

The dewpoint here will remain high from now until summer breaks in late September.

Here in Florida, there are 4 seasons:

Hot: March through May
F’ing Hot (Also known as Hurricane season, and in Orlando, tourist season): June through mid September
Still Hot: Mid September through Mid November
Snow Bird: Mid November through February

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. That’s why Floridians usually mow the grass starting at 8am. The combination of heat and the inability to shed heat through evaporation is a deadly combination. Beginning today, 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 the first day of summer until about the middle of September.

That’s why having a pool is such a great idea. My pool is a nice 84 degF throughout the summer, and it’s the only way to be outside while the “feels like” temperature is more than 90 or even 100 degrees.