Subtropical Storm Josephine forms in the Atlantic » Yale Climate Connections

by Irene Sans, Bob Henson and Jeff Masters, Yale Climate Connections
October 22, 2026

Subtropical Storm Josephine formed late Wednesday afternoon several hundred miles south of Cape Cod, Massachusetts, and is forecast to continue intensifying as it moves away from the United States, remaining south of Nova Scotia. Josephine became the 10th named system of the 2026 Atlantic hurricane season and the first subtropical storm to develop this season. This year’s tally for the Atlantic now stands at 10 named storms, one hurricane, one major hurricane, and an accumulated cyclone energy (ACE) index of 19, which is 17% of average for the date. Four of this year’s named storms have hit the U.S., with two of them being billion-dollar storms. One of them, Isaias, was a hurricane. On average, the U.S. sees three named storms make landfall during a season, with two of them being hurricanes.

A subtropical storm has both tropical and non-tropical (extratropical) characteristics. Subtropical storms usually derive their energy from a combination of ocean heat and temperature differences in the atmosphere. Unlike tropical systems, which typically have their strongest winds closer to the center, subtropical storms concentrate their strongest winds farther from the center. Subtropical storms also often have a warm core in the lower atmosphere, along with hybrid characteristics, and thunderstorms are usually displaced well away from the center.

The National Hurricane Center’s 11 a.m. AST update shows Josephine moving northeast at 12 mph (19 km/h), with maximum sustained winds of 65 mph (100 km). It is forecast to intensify to hurricane force while transitioning into an extratropical system, becoming wider and expanding its wind field, which would bring stronger maximum sustained winds to Nova Scotia on Friday as Josephine moves south of the area. Note that even if its sustained winds do reach hurricane strength, Josephine would not be designated a hurricane unless its structure were to morph from subtropical to tropical, which is not expected.

Over the last few days, local National Weather Service offices along the Mid-Atlantic and Northeast coast have continued issuing coastal flood and wind alerts. This is one reason why the National Hurricane Center has decided not to issue additional coastal alerts for Subtropical Storm Josephine, even though its winds are affecting parts of the Northeast. However, tropical storm warnings are in effect for offshore waters from the Mid-Atlantic through the Northeast and southeastern Canada.

Persistent onshore winds and waves from Josephine brought a storm surge in excess of two feet to North Carolina’s Outer Banks at Duck during high tide on both Wednesday and Thursday, causing “Minor” flooding that was high enough to cause extensive damage to the vulnerable road connecting the islands to the mainland, NC-12. The road is now closed, and emergency ferry service will be implemented until the road can be fixed. NC-12 was also damaged during a nor’easter in September, closing for a week for emergency repairs.

Strong winds are expected to continue affecting offshore waters and coastal regions, with numerous gale warnings remaining in effect through at least Friday afternoon, especially across coastal New England. Winds will mainly be from the north, with gusts up to 35 knots (about 40 mph). Seas could reach as high as 14 feet, particularly in the coastal waters near Nantucket, Massachusetts.

Forecast for Josephine

Josephine will have a short life as a named storm. It will continue moving over relatively warm waters associated with parts of the Gulf Stream today and Friday morning, which could provide enough energy for Josephine to intensify before it transitions into an extratropical system with hurricane-force winds, possibly by late Thursday or early Friday morning. As the system becomes extratropical, it will transition toward a cold-core structure and expand significantly as it moves into higher latitudes. A large trough exiting the United States will continue pushing Josephine eastward and away from the U.S. and southeastern Canada, allowing the storm to pick up speed.

Josephine will gradually lose its tropical characteristics as it moves over much cooler waters. The storm will likely continue racing eastward throughout the weekend, remaining more than 150 miles south of St. John’s, Newfoundland and Labrador, Canada. By Sunday, a larger low-pressure system to the north is expected to absorb Josephine, bringing its life cycle to an end.

Notable subtropical storms in the Atlantic

One of the earliest officially documented Atlantic subtropical storms was Subtropical Storm One in 1968. Not every Atlantic hurricane season produces a subtropical storm. On average, the North Atlantic officially recognizes about one subtropical storm each hurricane season.

However, a study published in the AMS Journal of Climate identified an average of 4.4 subtropical cyclones per year in the North Atlantic between 1958 and 2002. This higher number reflects the researchers’ identification of additional hybrid cyclones through atmospheric analysis.

In 2025, the North Atlantic hurricane season featured one subtropical storm, Karen, which developed over the north-central Atlantic, just west of the Azores. Karen was a very short-lived subtropical storm, lasting only two days after being named on October 9. Karen was particularly unusual because it formed farther north (latitude 44.5°N) than any other tropical or subtropical cyclone in the National Hurricane Center’s historical records.

Indian Ocean tropical cyclone expected this weekend

The Atlantic isn’t the only basin experiencing a remarkably quiet tropical cyclone season. The North Indian Ocean has seen only one named storm: a short-lived September tropical storm that peaked with top winds of 50 mph, which brought the seasonal tally of accumulated cyclone energy (ACE) to 1.0. Typically, the North Indian Ocean sees three named storms, one hurricane-strength storm, and an accumulated cyclone index (ACE) of 12 by this point in the season.

That is about to change. India’s Southwest monsoon ended on October 15, finishing with about a 13% rainfall deficit, according to the India Meteorology Department. Since the monsoon suppresses tropical cyclone formation, the end of the monsoon opens the opportunity for tropical cyclones to form in the North Indian Ocean’s Bay of Bengal and Arabian Sea. Our top tropical cyclone genesis models are predicting that a hurricane-strength cyclone will form on the east side of the Bay of Bengal this weekend, and track to the west or northwest, making landfall in India later in the week.

Vance forms in the Eastern Pacific

The latest entry in the Eastern Pacific’s hyperactive hurricane season, Tropical Storm Vance, was named at 5 p.m. EDT Wednesday and was already a 60-mph (95-km/h) tropical storm as of 11 a.m. EDT Thursday.

Centered about 500 mi. (800 km) south of Acapulco, Mexico, Vance was drifting northwest at 3 mph (6 km/h). Wind shear is predicted to remain light along Vance’s path at least into Friday, and Vance is passing through a very moist atmosphere and over very warm waters of 29-30 degrees Celsius (84-86 degrees Fahrenheit). Models agree on rapid intensification, and Vance is predicted to be a major Category 3 hurricane by Saturday as it takes a north-northwest track. By early next week, Vance could be approaching the same stretch of coast along Jalisco state that was sideswiped earlier this month by hurricanes Simon and Trudy. By that point, Vance will be traveling over water churned up by those and other storms, and it may be experiencing stretches of increased wind shear, both of which could blunt its strength.

Vance is the 22nd named storm in the Eastern Pacific this year, which leaves just four names on the 2026 list (Winnie, Xavier, Yolanda, and Zeke). The record for the Eastern Pacific is 26 named storms in 1992. As of Thursday, the basin had racked up 336 units of accumulated cyclone energy; that’s 271% of normal for the date, and already more than any other full Eastern Pacific season in data going back to 1949 (old record: 318.1 in 1998). If Vance becomes a major hurricane, it would be the basin’s 11th of the year, tying it with 2015 for the most major hurricanes in a season.

Southeast U.S. bracing for this weekend’s king tides

The highest tides of the year for much of the Southeast U.S. coast — the king tides — will be coming early next week during the period spanning the full moon (Oct. 25) and lunar perigee (Oct. 28). Perigee is when the moon is at its closest distance to the Earth during the month. In the lead-up to the king tides, a period of strong onshore winds will be setting up along the Southeast U.S. coast, caused by a strong high-pressure system to the north and low pressure offshore, creating a substantial pressure gradient. Winds of 25-35 mph (20-30 knots) are predicted along the Southeast coast on Sunday (Fig. 3), during the full moon, which will cause significant damaging flooding. Heavy coastal rains are predicted Saturday through Monday, and the runoff from these rains will further exacerbate coastal flooding by causing a compound flood event (see our August post, The floods of the future won’t come one at a time, to learn how climate change is increasing the threat of these types of flood events). NOAA is forecasting some of the highest water levels in 10 years along portions of the Southeast coast, including Miami, early next week.

The king tides during the full moon in late September also brought very high water levels to Miami during three consecutive high tide cycles. The tide level of 2.29 feet above high tide (MHHW) on Sep. 27 was just 0.19 feet below the threshold for “Major” flooding, and the city’s highest water level in 10 years, since Hurricane Irma brought the city’s last “major” flood episode of waters 3.57 feet above MHHW on Sep. 10, 2017. According to the latest forecast from the European model ensemble (see Bluesky post by Brian McNoldy above), water levels on Sunday and Monday are predicted to be about 2.2 feet above MHHW, which would be Miami’s third and fourth-highest water levels of the past 10 years.

The entire Southeast U.S. coast, not just Florida, will be seeing flooding from the king tides this weekend. For example, the high tide on Sunday morning in Charleston, SC, is predicted to bring the highest water levels of the year, just 0.1 foot below the “Major” flood threshold. NOAA advises that at this level, “Widespread flooding occurs in downtown Charleston with numerous roads flooded and impassable and some impact to structures. Impacts become more extensive all along the southeast South Carolina coast including erosion at area beaches, with limited or no access to docks, piers, and some islands.”

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