Jan 4th
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Infrared

  • The
    Big
    Freeze
    and the
    Slow
    Thaw

    Satellite images show a Philly blanketed in snow, rivers frozen solid, and eventually a city slowly thawing.

    Published

  • This is a satellite photo of Philadelphia taken on Jan. 4. The city had trace amounts of snow on rooftops following a brief snow shower in mid-December.

  • Two weeks later, on Jan. 19, Philly would be covered by a 4-inch dusting of snow. A gentle prelude to wrathful winter weeks that were to come.

  • One week later, the biggest snowstorm in 10 years left Philly with up to 8 inches of snow on the ground. This photo taken on Jan. 29 shows that any remaining parts of the city that weren’t already snowy were now covered.

  • As temperatures dipped down to single digits, the Schuylkill River down to the Passyunk Avenue Bridge was completely frozen over.

    The Schuylkill froze first because it is relatively shallow and still compared to the Delaware. “Shallow water freezes faster than deeper water because water that cools at the surface becomes more dense and sinks and is replaced by warmer water from below,” said Jonathan Edwards-Opperman, a physical scientist for the U.S. National Ice Center.

  • Edwards-Opperman also said that ice will form faster in “parts of the river that are more sheltered from winds or if currents are weaker near parts of the shoreline.”

    This explains why inland waters like the Cooper River and shielded water like that around Petty Island froze quickly.

  • By Feb. 8, the mountains of snow would solidify. With such sustained cold temperatures, the rest of the Delaware began to freeze as well.

    Snow and ice debris is piled along the Camden waterfront in Camden, N.J., framing the Philadelphia skyline across the Delaware River, Thursday, Feb. 5, 2026.

  • This infrared image shows the extent to which the Delaware froze over. Large chunks of ice around the Port of Philadelphia blocked barges loaded with salt intended for treating Philadelphia roads.

  • Before Feb. 13, the U.S. Coast Guard’s cutting operations cleared a lot of ice around the Port.

    Ray Kruzdlo, senior service hydrologist at the National Weather Service in Mount Holly, hypothesizes that “as the cargo ships or tankers worked through the ice, the ice broke up and then moved around or got flushed out.”

  • Meanwhile, the Delaware began to freeze between the Walt Whitman and Ben Franklin Bridges. Though it may seem the downstream ice drifted north, the new ice likely formed as relatively frigid upstream water flowed downriver.

    A view of broken ice in the freezing waters of the Delaware river are seen near the Ben Franklin Bridge in Camden, N.J., Monday, January 24, 2022

  • According to Amy Shallcross, Delaware River Basin Commission manager of water resource operation, U.S. Geological Survey data from temperature gauges at Chester, and Fort Mifflin, Trenton ↗ shows that the lower end of the river warmed earlier first. Chester recorded above-freezing temperatures a full week before upstream waters at Trenton did.

    “Water in the bay or in the lower part of the river is not as deep, and so it can freeze [and thaw] easier. If we got colder water from upstream, that might be why there was more freezing in the Philadelphia area,” said Shallcross.

  • After almost two weeks of overcast weather that obscured satellite imagery and a brief whiteout that left an additional 12 inches of snow on the ground, the city is finally clear. The recent snow melted almost immediately due to warm winter weather, and by Feb. 28, Philly had finally recovered from its long-lasting freeze.

  • Explore what the region looked like in the past few weeks.

    January 4January 19January 29February 8February 13February 28

    NaturalInfrared
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According to Shallcross, the last time Philadelphia’s rivers froze over was in 2018. However, it was nowhere as cold or severe, as the temperature was just below freezing.

“I don't think we've experienced that long of a cold snap that came about that quickly. And so it really was an unusual situation that we've just experienced,” said Shallcross.

Late January’s snow stuck around for way longer

Daily snow depth in Philadelphia. Source: the National Oceanic and Atmospheric Administration, measured at Philadelphia International Airport.

2"4"6"8"10"12"
DecJanFeb
Dec 15
Jan 26
Feb 23

The major freeze following the late January snowstorm meant that snow stuck around for three weeks. In contrast, the storm of late February was an example of how even larger snowfalls in Philadelphia can disappear quickly if the weather cooperates in the days following the storm. 12 inches of snow on the ground melted away in just a few days, as temperatures hovered in the 40s following the storm.

Fair to say that it’s been a harsh winter. After all, Punxsutawney Phil did see his shadow, and so far he’s been proven right. Thankfully, we’re not far away from spring.

Staff Contributors

  • Design, Development, and Reporting: Jasen Lo
  • Editing: Sam Morris
  • Photography: European Space Agency Copernicus Satellite Imagery
  • Copy editing: Brian Leighton

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