Weather Blog: August 18, 2025 8 AM (Tropics)

POWERFUL HURRICANE ERIN WILL BRING HIGH SURF AND DANGEROUS RIP CURRENTS TO THE U.S. EAST COAST THIS WEEK

Erin Update as of Monday Morning August 18

Major Hurricane Erin remains in an environment of weak wind shear and warm sea surface temperatures and has begun to increase in size.  As Erin gains latitude later this week, it will encounter increasing vertical wind shear and will eventually begin a gradual weakening trend as it recurves to the north and northeast and then accelerates into the North Atlantic.

As noted in the prior blog, Erin will continue to increase in size over the coming few days.  This is indicated by various computer models and is fairly typical for major hurricanes gaining latitude.   A consequence of an increase in size is that the storm will pack a significantly larger envelope of tropical storm and hurricane force winds.  This in turn will cause an expanding area of very high wind-driven waves that will then propagate long distances away from the storm in the form of large swells.  This will likely be the most consequential impact on the U.S. and Atlantic Canada coastlines.

Both global and hurricane-centric models depict Erin recurving to the northwest, north, and then northeast this week.  The consensus of models brings Erin to between 70W and 75W before recurving rather sharply to the northeast.  There is good model consensus that Erin will pass several hundred miles southeast of Nantucket Thursday evening.  Confidence in this recurvature is high.  There will be a series of upper troughs (often referred to by meteorologists as “short waves”) that will traverse across Canada and the northern United States this week.  These upper troughs, embedded in a larger scale west to east zonal flow, will act to weaken the west side of the subtropical high pressure ridge that has steered Erin to the west-northwest until now (Monday) and create a channel for Erin to turn northward before reaching the U.S. east coast.  That broader west to east flow across the northern U.S. will also cause Erin to turn sharply to the northeast, if not east-northeast, while still well south of New England.  Thus, a U.S. landfall from Erin is not expected.

Erin will pass a considerable distance west of Bermuda but may still pass close enough for strong wind gusts and bands of heavy rain in addition to very high surf.

Although remaining offshore, Erin may brush North Carolina’s outer banks with tropical storm force winds and possibly heavy rain from Erin’s outer bands.  In addition, large breakers that may approach 20 feet in height will crash upon the beaches of the outer banks..

Erin will pass well offshore of New England, but the combination of an expansion in size and the pressure gradient between Erin and high pressure centered in southern Canada will produce a rather brisk northeast wind over all of southeast New England.  In fact, tropical storm or gale force gusts are possible Thursday afternoon and night across some of the coastal waters, especially just southeast of Chatham and Nantucket.

Impacts and Recommended Actions Regarding Erin

High surf and dangerous rip currents will impact nearly all of the exposed U.S. east coast this coming week.  For southern New England, large swells resulting in high surf and dangerous rip currents will likely reach the southern New England exposed south facing shorelines by late Tuesday and spread to southeast facing shorelines by Wednesday and remain a concern through the rest of the week.  The high surf and dangerous rip currents will likely impact such locations as the RI exposed south coast beaches, Horseneck Beach in southern MA, Martha’s Vineyard’s South Beach and other exposed south-facing beaches, exposed south and east facing beaches on Nantucket, and the beaches along the ocean side of Cape Cod.  An onshore wind in addition to the swells may also increase the risk of higher than normal surf and dangerous rip currents for some east and southeast facing beaches north of Cape Cod (all the way to downeast Maine) by late in the week.  The National Weather Service will likely be issuing a High Surf Advisory for ocean exposed beaches of New England.  Swimmers and inexperienced surfers should be extremely cautious and follow any lifeguard recommendations, if not stay out of the water entirely.

Although heavy rain bands associated with Erin will likely remain well offshore of New England, there will be a stiff northeast wind by Thursday due to the pressure gradient noted between Erin and high pressure centered over southern Canada.

A significant maritime impact is expected.  Swells above 10 feet will propagate into the southeast New England coastal waters during the mid to late week time frame, and these swells will likely result in the issuance of Small Craft Advisories. The northeast wind flow (due to the pressure gradient between the hurricane and high pressure to the northwest) may be strong enough to meet Small Craft Advisory criteria even in areas protected or partially protected by the swells by late Wednesday or Thursday.  Tropical storm force gusts and waves over 12 feet may occur a short distance southeast of Nantucket during Thursday afternoon and night.  The combination of a rather strong northeast wind and high southerly swells may also result in a chaotic sea with steep wave profiles over the waters south and southeast of New England.  As noted in prior blogs, mariners planning any offshore trips this coming week should closely monitor later National Weather Service forecasts and be prepared to adjust their plans.  In addition, small boat owners may wish to check moorings in Cape and Island anchorages.

Further Information

The National Weather Service monitors the weather 24/7 and updates forecasts, watches, and warnings as necessary.  For most of southern New England, refer to your local Weather Forecast Office for the latest forecast/warning information at weather.gov/box.  For information from other Weather Forecast Offices, go to weather.gov and click on the location of interest on the map.  For the latest information on Atlantic basin hurricane activity, access the National Hurricane Center website at nhc.noaa.gov.

This will probably be the last blog on Erin unless a significantly greater impact to any part of the U.S. due to Erin becomes a concern.  As always and especially if a mariner, check the latest forecast information from the National Weather Service or your private weather source before undertaking a venture that might increase your vulnerability to the elements.

The motivation to start a blog on Erin was primarily to use this storm as a reminder to prepare or review plans of action in the event of a serious hurricane threat.  We are now heading into the peak of the hurricane season and will likely be monitoring future hurricanes over the next month or two.  In fact, the National Hurricane Center is now monitoring an area of showers and thunderstorms associated with a tropical wave over the eastern Atlantic.  Although presently disorganized, this system has the potential to develop into a tropical depression later in the week.  A blog will be issued on this new system if it should eventually pose a serious threat to any U.S. coastal area.

About this Blog and Disclaimer

These weather messages are issued when there is a potential risk of hazardous weather to southern New England and serve to provide background information regarding the significant weather with somewhat of an educational slant.  In the case of hurricanes, the author will attempt to issue a message when any portion of the United States coastline may be impacted.  It’s intended to complement and not serve as an alternative to official forecasts issued by the National Weather Service.  Readers are urged to check National Weather Service forecasts and warnings for the most timely and updated weather information.  This weather message is solely produced by the listed author and does not constitute an official product of the Blue Hill Observatory and Science Center (BHOSC).

The frequency of this blog will depend upon the nature of the weather threat and availability of the author.  Thus, for the latest information on weather forecasts and warnings, refer to the National Weather Service, which monitors and forecasts the weather 24/7.

Blue Hill Observatory and Science Center (BHOSC)

The BHOSC maintains a continuous daily observation record that dates from February 1, 1885 without interruption and provides educational information on weather and climate to area students and the community at large.  Your support of BHOSC is much appreciated and enables this nonprofit organization to maintain the long-term climate record at the Blue Hill Observatory (longest continuous record in North America) and provide valuable educational resources on weather and climate via outreach to schools, site visits/tours, webinars, and conferences.  For more information on the Blue Hill Observatory and Science Center, explore bluehill.org.

Next Blog

This will probably be the final blog on Erin unless forecast changes indicate a more serious threat to any U.S. land mass.  Monitor the latest National Weather Service forecasts for specifics as Erin makes its closest approach.  Since we are just now entering the peak of the hurricane season, there will likely be future storms to monitor in the coming weeks.

Message issued by:
Bob Thompson
Retired National Weather Service Meteorologist
Blue Hill Observatory and Science Center Board member