Some things you might not know about the weather on the 4th of July…
“I’m going to Disney World” wasn’t an option in 1776. So what does Thomas Jefferson do after authoring the Declaration of Independence? He notes the weather. The common narrative states that it was very hot and humid in Philadelphia on July 4, 1776. Historians have described it as “sweltering” and “stifling.” But, Jefferson’s own weather records show that’s not exactly true. According to the Library of Congress, on July 4, 1776, he observed temperatures of 68F at 6am, 72F at 9am, 76F at 1pm and 73F at 9pm. An afternoon temperature of 76 in early July in Philadelphia would be quite a bit cooler than average. However, Jefferson began taking weather observations in Philadelphia on July 1, 1776 and his weather records show it was warmer in the days prior to July 4th. Not to mention, if you are wearing a heavy suit and a wig, and having heated arguments in a State House without air conditioning, it was probably uncomfortable regardless of the weather outside.
July 4, 2016 happens to be the day that Earth is at aphelion, the farthest point in its orbit from the sun. Earth’s orbit isn’t a perfect circle, so there are times of the year when Earth is a bit closer to the sun (perihelion) and times when it is a bit farther from the sun (aphelion). Perihelion happens in early January and aphelion in early July. This year aphelion happens to fall on Independence Day. Yes, that’s right…Earth is farther away from the sun in the middle of summer for the Northern Hemisphere. The tilt of the Northern Hemisphere toward the Sun has far more impact on our climate than a few million miles.
How about the weather this 4th of July? Another thing you might not know yet, to quote the National Weather Service, there’s been “quite a shift since last night’s forecast.” I couldn’t say it better myself.
Sunday will be like Saturday, only a few degrees warmer. That hasn’t changed.
Monday will be even warmer, but the humidity levels don’t change, so it will be comfortably warm by summer standards. Expect high temperatures in the upper 80s for most, low 80s for the Cape. Around the time the fireworks launch Monday evening temperatures will have cooled to the mid 70s. Skies will be partly cloudy at that time but clouds will take over late Monday night.
The storm that we once predicted would pass through the Baltimore-Washington area on Monday now looks like it will pass through New Jersey…close enough to bring some rain to Southern New England. But don’t worry, that won’t reach us until Tuesday morning. So, your 4th plans are still OK.
Wednesday still looks hot. But the forecast for Thursday has also changed a bit…it now looks like we might see some pop-up showers and thunderstorms Thursday afternoon. Depending on if/when those showers and thunderstorms develop, Wednesday might be a touch hotter than Thursday but both days will be hot and humid.
A frontal system approaches the area on Friday and hangs out into the weekend. That will bring us a chance of scattered showers and thunderstorms for Friday and Saturday. Neither day will be a washout as these will be hit or miss showers.
Bottom-line…the forecast for the coming week that looked bone dry yesterday now has several chances for some rain. That’s not necessarily a bad thing given the drought situation…as long as the rain holds off until after Monday.