The following "Director's Note" is from the Sarasota Bay Estuary Program's Dave Tomasko:

Seawater Temperatures

It’s not your imagination – it is really hot out there. Let’s put aside (for now) the causes of what we’ll be discussing here, and just focus on the outcomes – which is that our air and water temperatures are increasing.

For us to discuss temperature trends, it’s important to keep in mind the data sets upon which we can make conclusions. Any location with an airport (like Sarasota) will have a great data set on air temperature, because it is an important consideration related to the density of air, and thus on flight characteristics. I earned my pilot’s license back in 1998 (single-engine land) and never liked flying in the summer – the little planes (with their little engines) we rented struggled to get aloft on hot days, since hot air is less dense, and generates less lift at the same airspeed.

So what does our air temperature data conclude? That it is getting warmer over time. The plot below compares each month’s average air temperature to the average for that month for the period of 1901 to 2000. If any given month is spot-on average, the month shows up white. Cooler would be blue, and warmer would be yellow. Warmest still would be brown. As you can see, the prior century had a fairly even mixture of blues and yellows, with a few browns. Over the last 20 to 40 years, it’s mostly yellow and browns. We used to average about 2 to 3 freezing temperatures per year in Sarasota, but from 2011 to 2020, we had only 3 the entire decade – the lowest amount of days with freezing temperatures over the 11 decades with such data. We used to start August days with temperatures in the 60s, every once in a while. But we haven’t had a single hour of a single day in any August month over the past 20 years lower than 70 degrees.