We’ve been waiting for a week like this in Philly; so have the tree pollen. With June-like temperatures expect a pollen harvest.

With temperatures heading toward June levels, and rain hardly a rumor, this might well become the most splendidly gorgeous weather week of the last seven months. And for the millions of allergy sufferers in the Philadelphia region and the rest of the Mid-Atlantic, it might well be the most tormenting.

Allergists are warning that the trees are primed for a major pollen frenzy, thanks to outstanding prep work on the part of winter and excellent looming flight conditions for the ultra-tiny pollen grains.

“I’m constantly walking outside, looking at the trees,” said Marc Goldstein, allergist at the Asthma Center in Center City. “You can see things are happening.”

Indeed they are. As the blossoms fade and call it a season, the trees are swelling with that delightful first-green shading power, and are greatly in the mood to spread their progeny. That likely will mean an outbreak of sneezing, itchy eyes, and assorted discomforts. (Note: They do not include fever, which can be a symptom of COVID-19, which isn’t associated with itchiness.)

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Given the forecast for temperatures into the 80s by Wednesday and gentle breezes, for those sensitive to tree pollen, “It’s going to be a tough week,” said Jonathan O’Brien, a meteorologist with the National Weather Service Office in Mount Holly.

Said Leonard Bielory, an allergist in Springfield, N.J., who is a National Allergy Bureau-certified pollen counter, “The pollen will be intense.” Thanks to long-melted, generous February snows on both sides of the river, the trees have ingested “lots of nutrients,” he said.

He added that the potential would be worth a weather service-style alert if such a system existed in the pollen universe. It doesn’t, for a variety of reasons.

Trees rely on winds to disperse pollen, which is the male fertilizing agent, and they have to emit mass quantities of it since only a small percentage of the yellowish-green grains will yield seed production. No tree is going to take root on your car roof or windshield.

The victims of this scatter-gun approach are millions of allergy sufferers whose bodies view the grains as invaders. That causes their immune systems to go into hyper-protective mode by producing antibodies that set off sneezing, general stuffiness, and beyond-annoying itchiness in the nose and mouth and, in some cases, the ears.

Typically, the tree season begins in mid-March and approaches its crescendo height right about now. Cooler weather more or less kills the mood and inhibits dispersal. Temperatures around here in April have been close to normal, without a run of seriously warm days.

That evidently is about to change as high pressure builds over the East, and this could be a banner week for holders of stock in Kimberly-Clark, the outfit that owns Kleenex.

We don’t, precisely. Unlike weather, the nation has no organized pollen-observation network. Credible coverage is sparse.

Around here, the Asthma Center, which supplies daily counts to The Inquirer, uses an automated “machine-learning” device to estimate amounts and pollen types and posts counts daily. The readings are taken once a day between 6 and 7 a.m.

The device has not yet received the allergy bureau’s seal of approval, but Goldstein, chief of allergy and immunology at Pennsylvania Hospital, said that it has performed well in tests and that he is confident that it is measuring accurately.

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In Mount Laurel, Burlington County, Donald Dvorin, of the Asthma and Allergy Doctors practice, uses a traditional trapping method in which the grains are sucked into a coin-slot-size slit and attach to a microscope slide coated with an adhesive.

He then analyzes the prisoners, and the result is the amount of pollen that has entered the trap in the previous 24 hours. His are the only NAB-certified counts in the region.

Neither systems are predictive, however, and pollen concentrations can vary radically throughout the day depending on the weather and other variables that aren’t completely understood.

The predictability of pollen remains a subject of research and debate. Timothy Craig, professor of medicine and pediatrics in allergy and immunology at Penn State Health Milton S. Hershey Medical Center, said that when he hears someone claim the ability to predict pollen levels three days out, his reaction is, “Like heck you can.”

One 2017 study of predictive pollen apps in Europe showed quite mixed results. Bielory said he has had some success with 72-hour forecasts, adding that an accurate weather forecast would be about 90% of the battle. But the atmosphere has been known to mock those three-day weather forecasts on occasion.

The seasons have some variations in peaks and valleys from year to year, according to available data, but it’s a decent bet that a warm, dry day in late April with a breeze is going to yield high counts.

When it’s raining or the atmosphere generally is moisture-laden, that pretty much closes the airports.

But pollen experts say other variables are in play, including volumetric differences from year to year. For reasons that aren’t clear, the trees just decide not to expend the same amount of effort. One other variable is the human being.

Symptoms can be worse on an overall low-count day, and vice versa. Species can affect individual sufferers differently. For example, a high concentration of oak pollens — which dominated last week, Dvorin said — wouldn’t be a big deal for those who aren’t allergic to oaks. An overall high count, however, increases the odds of torment.

Allergists recommend that patients begin using medications — for example, steroidal nose sprays and inhalers — well before the season starts.

If it’s too late, tissues and a wide selection of over-the-counter remedies are available. And one thing you can do is the obvious: Avoid the stuff if at all possible.

Stay inside when counts are high, and if you are outside, you can do something totally different: Wear a mask. When you come back inside take a shower and change clothes.

Keep the windows shut and turn on the air-conditioning if it’s warm enough; that will clean and dry the indoor air.

The forecast suggests that it could be warm enough to kick-start that a/c later in the week. That also could kick off a pollen storm. Said Dvorin, “That will bring it out.”