It's already summertime in the Northern Hemisphere, according to one definition, but there are several different definitions of summer.
The calendar may say that summer begins on June 21, but it's already started, depending on which definition you follow. Memorial Day is the unofficial beginning to summer for some, since many summer activities, such as swimming, are underway.
Definitions of Summer
Right now, it's solar summer, the quarter of the year where the most energy from the sun is entering the Northern Hemisphere, AccuWeather.com Meteorologist Brian Edwards said. Solar summer, which is centered around June 21, runs from early May to July.
The start date to another definition of summer, meteorological summer, is quickly approaching.
"Meteorological summer is the quarter of the year with the warmest average temperature, running from June to August," Edwards said.
For those who wish summer wouldn't end, there's always astronomical summer -- the longest summer of all.
"Astronomical summer starts out at the summer solstice," Edwards said. "It is when the incoming solar energy is at its maximum in the Northern Hemisphere. It runs until mid-September until the autumnal equinox, the time when solar energy is equal in both hemispheres."
Summer Weather Myths
Summer means warmer weather, sunshine and outdoor activities. It also means an increased chance of thunderstorms and a raised awareness of "heat lightning."
However, heat lightning doesn't exist, Edwards said. What people are seeing, maybe even on a clear night, is the lightning from distant thunderstorms.
"But they are too far away to hear the thunder," Edwards said.
"I've been in Pennsylvania, looked to the south and saw lightning from storms in the Carolinas, over 400 miles away," he said.
One other summer myth is that lightning can't occur in an area with clear skies -- the so-called "bolt out of the blue."
"The bolt happens first and then the sound. All of a sudden, 'BOOM!', it hits," Edwards said.
A random lightning strike can occur 10 to 15 miles ahead of a thunderstorm, he said. These bolts typically strike from a thunderstorm anvil cloud, which can drift away from the parent thunderstorm cloud.
People need to monitor their surroundings for rapidly changing weather conditions this time of year. One way you can follow the Minute by Minute™ weather forecast is to click on AccuWeather's MinuteCast™.