May was hot. Thank you for coming to my TED Talk.

May 2019 Temperatures

The start of another month means the National Weather Service has issued its preliminary monthly climate summary for the previous month. And as anyone who survived the past week can attest, May was hotter than normal.

May 28th, 2019 was the hottest day of the month, officially topping out at 97 degrees in Orlando. This is based on the official temperature at the airport, so it might have been hotter or cooler where you are (although your car thermometer is a lying liar… but that’s another post for another day). We had 17 days… more than half of the month… with a high temperature at or above 90 degrees. The “coldest” day was May 18th, which bottomed out at a positively frosty 65 degrees. The monthly records (102° record high in 1945 and 47° record low in 1925) are safe for another year. Averaging out each day’s high temperature gets us to an average maximum temperature of 90 degrees, which is about two degrees higher than normal (measured from 1981-2010), and about 5 degrees higher than May 2018. The average low temperature was 69.5 degrees, about three degrees warmer than normal.

Daily Rainfall Graph
Daily Rainfall Totals for May 2019

Given the hot and dry spell at the end of the month, you might not have realized that May was a bit wetter than normal… 4.34″ of rain, with 1.27″ of that coming on May 14th alone. A typical May only has 3.45″ of rain. That said, there weren’t too many days when we saw actual rainfall, at least at the airport. And May 2019 was much dryer than May 2018, by about 3″. You’ll be shocked to know that the NWS says there was no snow in Orlando last month. Maybe we’ll have better luck in June.

Can you take out a second mortgage to pay your Duke Energy bill? Asking for a friend.

Energy Usage
Now to the real impact… your power bill, God rest its soul. Take a look at the past week’s usage graph from my air conditioner. I’m willing to bet yours is higher than normal too. It’s no wonder that Kissimmee Utility Authority customers set a record on May 28th, using more electricity that day than any other day in the past 118 years. Luckily, Science™ lets us quantify all of this temperature-and-electricity hoopla. There’s a rather confusing little unit of measure called “Degree Days” that generally describes how much energy the weather causes us to use on air conditioning or heating. To get that number, you compare the average of a particular date’s actual temperature readings against a set target temperature (usually 65°)… and the difference equals the number of Degree Days … “Cooling Degree Days” if the real temp is hotter than the target, or “Heating Degree Days” if it’s colder than the target. A calendar day can have more than one degree day assigned to it. For instance, If the target temp is 65° and it was 70° outside, that one calendar day = five Cooling Degree Days (70° minus 65° = 5°). A normal May in Orlando has a total of 380 Cooling Degree Days. Last May was right on target. This year, it was 466, or 86 more than normal. For the year so far we’re 286 Cooling Degree Days higher than normal, at 1087. In plain English, it got hotter sooner.

30-Day Outlook
So what does June hold in store? According to the NWS Climate Prediction Center, there’s at least a 50% chance that Florida’s temperatures will be higher than normal over the next 30 days. If anyone needs me, I’ll be submerged in ice water through December.

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