Philly’s weather has taken a turn for the wetter this summer. Here’s why.

Federal and state officials, farmers, and gardeners have been understandably anxious about precipitation deficits. In fact, as of Monday, the entire state of Pennsylvania remained under a “drought watch,” with residents asked to conserve water.

But if the atmosphere has an attention span, it has done a decent job of concealing it, and during the weekend, things began changing in a hurry here and elsewhere in the East. While June rain is notoriously capricious — Monday’s storm total varied widely around Philly — it appears that the taps may stay active for a while. Flood watches are up again from noon to midnight Tuesday for the city and its neighboring Pennsylvania counties.

“We sort of flipped that switch,” said Rich Otto, a meteorologist with the government’s Weather Prediction Center, in College Park, Md.

» READ MORE: More storms expected in Philly Tuesday afternoon, with flooding possible

The atmosphere fired a warning shot Friday over Philly when it swelled with moisture, setting off rounds of showers that continued through the weekend. The air became so saturated so quickly that if you spent time outside and felt like you were coming down with something, you had plenty of company.

“It’s a little bit of a shock to folks along the East Coast,” said Otto.

Agreed Paul Pastelok, a veteran long-range forecaster at AccuWeather Inc., in State College, “This kind of shocks me.” He added that after watching his son play in a soccer tournament on Saturday, when he got home, he was inert. “And I wasn’t even playing. … I said to my wife, ‘I’m not going back out there.’”

» READ MORE: Pa. declared a drought watch on June 15, and it's still in effect

Yes, says Alex Staarmann, a meteorologist with the National Weather Service in Mount Holly, and other forecasters. These levels of humidity and heat are rather typical June fare.

What wasn’t typical was the period from May 1 to the summer solstice. Last month was the driest May on record in Philly, and in the 37-day period that ended June 11, the city officially received a paltry a quarter-inch of rain.

» READ MORE: May was bone dry in Philly

It also had been quite cool. Although the last few days of June should feature near normal temperatures, this almost certainly will mark the first time in 20 years that average temperatures — the daily highs and lows — for both May and June will have been below normal.

On Friday, hair-frizzing humidities rose, and the dew point — that’s the measure of absolute moisture in the atmosphere — soared to heat-wave levels, where they stayed through Monday, giving thunderstorms a rich water supply.

Usually, nature allows us a period of thermal adjustment before subjecting us to the summer steam bath. It didn’t happen this time.

“We don’t have springs like this,” said Otto. “It’s been a dramatic change.”

“We’ve had sort of a ‘blocky’ pattern,” said Otto.

Ordinarily weather systems move west to east, but the flow has been jammed up by an unusual succession of upper-air areas of low pressure over eastern North America, meteorologists said.

Until recently, they were keeping it cool and dry in the East by cutting off moisture supplies from the Gulf of Mexico.

Winds circulate counterclockwise around the centers of those systems. Earlier in the month, one was centered in northern New England to the east of Philadelphia, and winds from the north were importing smoke-filled air from the burning woods of Quebec to the I-95 corridor.

The latest system is well to the west, and its winds from the southwest to the east of the center have been driving moisture-laden air northward. Three-day rain totals through Sunday in Philadelphia were three times greater than those in the entire month of May.

» READ MORE: Flood warnings went up Friday in the Philly region

Innocent.

Its lack of influence was evident in the Atlantic tropics with a bump of tropical-storm activity in June, the opposite of what would be expected during El Niño, when waters in the subtropical Pacific become unusually warm. The heating of the overlying air generates upper-air winds from the west can shear off potential tropical storms in the Atlantic Basin.

» READ MORE: El Nino may have benign impacts on the hurricane season

El Niño impacts in the United States likely are weeks or months away, forecasters say.

More showers are likely Tuesday and Tuesday night around here, with a good shot that they’ll return on Wednesday.

Otto said that the atmospheric tea leaves suggest that the blistering heat in Texas and the Southwest “will begin to spread eastward.” But it looks like it will have to wait its turn in Philly.

So far, June has had only one day with 90-plus temperatures in Philly. The normal for June is six. In the short term, forecasters say, Thursday and Friday, could be on the spectacular side, with sun and highs in the 80s.

Then expect a return to the rinse and repeat cycle on the weekend, along with those heat-wave level dew points.

» READ MORE: The pre-season forecasts called for a toasty summer. It's early

“So, hey, welcome to summer,” said Otto. “This isn’t really unusual.”