A Primer on Hurricanes and Tropical Storms in the Mid-Atlantic

This primer is excerpted from Mid-Atlantic Regional Climate Impacts Summary and Outlook: Spring 2026.

Introduction

The Atlantic hurricane season runs from June 1 through November 30, with peak activity from August through October, when warm ocean temperatures and favorable atmospheric conditions support the majority of tropical cyclone development.¹ On average, the Atlantic basin produces about 14 named storms, 7 hurricanes, and 3 major hurricanes per season (1991–2020 climatology.²

Tropical systems are monitored from their earliest stages through their full lifecycle by NOAA's National Hurricane Center (NHC), which works in coordination with local National Weather Service (NWS) forecast offices to issue advisories, watches, and warnings.

Tropical Cyclones in the Mid-Atlantic

The Mid-Atlantic lies north of the Atlantic basin's main development region and historically experiences fewer tropical cyclones than the Gulf Coast or Southeast. From 1990 to 2017, the Mid-Atlantic and Northeast together received roughly 6% of all tropical storms and hurricanes affecting the continental United States annually.³ Within the regional record, September is the most active month, followed by August, and the seasonal distribution has remained relatively stable over time.⁴

In the Mid-Atlantic, the period from 2000 to 2030 saw nearly twice as many hurricanes affecting the region as the preceding two decades (1980–2000).⁵ The 2004 season remains the most active on record for the region.⁶

Despite the relatively low frequency, individual storms have produced some of the costliest disasters in U.S. history. Damage estimates from NOAA's National Centers for Environmental Information (NCEI) Billion-Dollar Disasters database (CPI-adjusted to 2024 dollars) include:⁷

• Hurricane Sandy (2012): ~$88 billion in total damage, with catastrophic surge along the New Jersey and New York coasts and significant impacts in Delaware, Maryland, and Virginia.
• Hurricane Ida (2021): ~$84 billion in total damage; remnants produced record flash flooding and tornadoes across Pennsylvania, New Jersey, New York, and Maryland, killing more than 50 people in the Northeast.
• Hurricane Floyd (1999): ~$12 billion in total damage; widespread inland flooding across the Mid-Atlantic.
• Hurricane Isabel (2003): ~$9 billion in total damage; produced major surge in the Chesapeake Bay and widespread wind damage from Virginia through Pennsylvania.
• Tropical Storm Lee (2011): ~$3.5 billion, with extensive inland flooding in Pennsylvania.

Storm Classifications

The NHC tracks low-pressure disturbances forming over the tropical Atlantic, Caribbean Sea, and Gulf of Mexico. Under favorable conditions—warm sea-surface temperatures, low vertical wind shear, and sufficient atmospheric moisture—these disturbances can organize into tropical cyclones. Classifications are based on maximum sustained (1-minute average) wind speeds at 10 meters above the surface.⁸

A tropical depression has an organized circulation and some thunderstorm activity, but lacks the wind strength and structural organization of stronger systems. Hurricane intensity is further described by the Saffir-Simpson Hurricane Wind Scale, which estimates potential property damage from Category 1 ("very dangerous winds") through Category 5 ("catastrophic damage").⁹

Source: NOAA

The Saffir-Simpson Hurricane Wind Scale for Categories 1 through 5:

• Category 1
  • Wind: 74 to 95 miles per hour
  • Damage: Very dangerous winds will produce some damage
• Category 2
  • Wind: 96 to 110 miles per hour
  • Damage: Extremely dangerous winds will cause extensive damage
• Category 3
  • Wind: 111 to 129 miles per hour
  • Damage: Devastating damage will occur
• Category 4
  • Wind: 130 to 156 miles per hour
  • Damage: Catastrophic damage will occur
• Category 5
  • Wind: 157 miles per hour or higher
  • Damage: Catastrophic damage will occur

A post-tropical cyclone has lost defining tropical features, such as a warm core or organized central convection, often transitioning into an extratropical system as it moves into cooler mid-latitude waters. Despite this transition, these systems can still produce significant impacts, including heavy rainfall, damaging winds, and coastal flooding. This distinction matters for the Mid-Atlantic, where many of the region's most damaging storms (including Hurricane Sandy) arrive as post-tropical or transitioning systems.

Tropical Cyclone Forecasting

Seasonal Outlooks

Forecasting begins in mid-May, before the official start of hurricane season, when NOAA's Climate Prediction Center issues its Atlantic Hurricane Season Outlook. These outlooks provide expected ranges for the number of named storms, hurricanes, major hurricanes, and the Accumulated Cyclone Energy (ACE) index, which combines storm frequency, intensity, and duration.¹⁰ Each season is categorized as below-normal, near-normal, or above-normal, and the outlook is updated in early August.

Season Type	Mean	Range of Named storms	Mean	Range of Hurricanes	Mean	Range of Major Hurricanes
Above-Normal	15.9	11 to 30	9.2	6 to 15	4.5	2 to 7
Near-Normal	11.7	6 to 18	6.2	3 to 9	2.2	1 to 4
Below-Normal	8.6	4 to 14	3.8	2 to 6	1.2	0 to 2

NOTE: This table is based on data from 1950–2000.

Importantly, seasonal outlooks predict basin-wide activity, not landfall. Key inputs include sea-surface temperatures, trade wind strength, vertical wind shear, the West African monsoon, and the El Niño–Southern Oscillation (ENSO) phase.

Real-Time Forecasting

Once a system develops, forecasters generally rely on satellite imagery, NOAA Hurricane Hunter aircraft observations, dropsondes, buoys, and an ensemble of dynamical and statistical computer models, combined with forecaster expertise.¹¹ The NHC labels each disturbance with a 7-day formation probability (<40%, 40–60%, or >60%).

When a tropical depression does form, the location, wind speeds, and movement are monitored. For active storms, the NHC issues forecasts of position and intensity, accompanied by the "cone of uncertainty". This cone shows the possible track of the system, with the cone and uncertainty in the forecast getting larger with forecast lead time (see Figure 8). Forecasting the track can be difficult because several factors including other weather systems will impact the movement of the tropical system. The cone widens with forecast lead time to reflect growing uncertainty.

Source: NWS National Hurricane Center

National Hurricane Center forecast cone map for Hurricane Milton in the Gulf of Mexico, dated Tuesday, October 8, 2024, at 8 a.m. CDT. The projected path of the storm is shown from the northwestern Caribbean and eastern Gulf of Mexico across Florida and then into the western Atlantic Ocean.

The plotted cone path contains the probable path of the storm center but does not show the size of the storm, and hazardous conditions can occur outside of the cone.

The forecast track begins in the southern Gulf of Mexico and moves generally east to east-northeast. Labeled forecast points include:

• 1 a.m. Tuesday, southwest of Florida near the Yucatan Channel region
• 1 a.m. Wednesday in the eastern Gulf of Mexico
• 1 p.m. Wednesday farther east in the Gulf
• 1 a.m. Thursday approaching the west coast of Florida
• 1 p.m. Thursday crossing central Florida
• 1 a.m. Friday just off the east coast of Florida
• 1 a.m. Saturday over the western Atlantic
• 1 a.m. Sunday farther northeast over the Atlantic

The cone widens over time, indicating increasing forecast uncertainty. The storm is shown strengthening over the Gulf as a major hurricane and then weakening after crossing Florida and moving into the Atlantic.

Track forecasts have improved substantially over the past several decades due to better models and observations. Intensity forecasts remain more challenging, particularly for rapid intensification, defined as an increase of at least 35 mph in 24 hours, because small changes in storm structure, ocean heat content, and wind shear can produce large differences in outcomes.¹²

Watches and Warnings

The NWS issues watches and warnings tied to specific hazards. In general, a watch indicates conditions are possible, while a warning indicates conditions are expected or occurring. In addition to what is listed below, flood and tornado watches and warnings can accompany tropical cyclones.

Wind-Based Alerts

• Tropical Storm Watch / Warning: Tropical-storm-force winds (39–73 mph) possible within 48 hours / expected within 36 hours.
• Hurricane Watch / Warning: Hurricane conditions possible within 48 hours / expected within 36 hours.
• Extreme Wind Warning: Major-hurricane-force sustained winds (typically eyewall winds) expected within one hour.

Source: Weather.gov

Tropical Storm & Hurricanes

Watches Versus Warnings

Watch

• Tropical storm and/or hurricane conditions are possible in the watch area.
• A watch is issued up to 48 hours in advance of tropical storm force winds.

Warning

• Tropical storm and/or hurricane conditions are expected in the warning area.
• A warning is issued up to 36 hours in advance of onset of tropical storm force winds.

Hurricane preparedness activities become difficult once winds reach tropical storm force. Watches and warnings are issued in advance of onset of tropical storm force winds, 39 to 73 miles per hour.

Storm Surge Alerts

Storm surge is the abnormal rise in coastal water levels generated by a storm's winds. It is the amount of additional water generated from a storm, on top of regular tidal fluctuations.¹³

• Storm Surge Watch / Warning: Possibility / danger of life-threatening inundation from rising water moving inland, generally within 48 / 36 hours.

Source: Weather.gov

Comparison of storm surge flooding to a nice weather day

Understanding Storm Surge Flooding

Storm surge flooding is often the greatest threat to life and property and directly accounts for about half of the deaths associated with tropical storms and hurricanes in the U.S. NOAA coastal flood forecasts are expressed as feet above ground level to best account for variations in land elevation and features, and to focus on potential impacts.

A storm surge pushes ocean water higher than the normal high tide mark, resulting in normally dry ground being inundated.

Nice Weather Day

In the case of a normal high tide, areas above the usual high tide mark remain dry.

Tropical Cyclone Impacts

These advisories, watches, and warnings are issued to help safeguard lives and property. Timely communication allows people to take necessary protective actions, such as securing windows, gathering supplies, and evacuating if needed. While not every storm makes landfall, a single storm can still result in significant impacts.

Flooding is a major impact hazard for both coastal and inland areas. Coastal flooding occurs as storm surge pushes ocean water onto normally dry land, while inland flooding occurs with heavy rainfall. These flooding scenarios can cause flash flooding, where a large amount of water rapidly inundates dry land, and can be deadly and destructive. Inland flooding can be an overlooked hazard of tropical systems, but recent storms have had record-breaking rainfall leading to evacuations and water rescues.

Tropical systems are defined by their sustained wind speeds, which can cause dangerous to catastrophic damage. In addition to knocking down trees and powerlines, the strongest winds can carry heavy objects and tear down buildings.

Tornadoes can also develop within tropical systems, adding another layer of danger to these already powerful storms. These tornadoes often form quickly, sometimes with little warning, as rainbands spiral inland from the main system. Tornadoes often form from the outer rain bands of a hurricane, especially in the right-front quadrant as the storm approaches or moves over land. Although they are typically weaker than those formed in other severe weather events, they can still cause significant localized damage to homes, trees, and power lines. Their sudden and scattered nature makes them especially hazardous, as they can strike areas that may not be experiencing the strongest winds from the system itself.

Tropical systems that remain offshore can still pose significant hazards to coastal areas, even without making landfall. These storms can generate powerful waves that lead to rough surf and dangerous swimming conditions along the shoreline. One of the most serious risks is the formation of rip currents—strong, fast-moving channels of water that can pull swimmers away from the beach and into deeper water. These conditions can persist for days as the system moves through the region, making it important for people to stay informed and exercise caution near the coast, even when skies may appear calm.

It is important to monitor forecasts closely and follow the guidance of local officials, as conditions can deteriorate rapidly. Tropical systems can affect large regions—often spanning multiple states—disrupting air travel, businesses, and daily life. Recovery can be slow, with damaged infrastructure taking months or even longer to rebuild. Impacts to agriculture may also lead to higher food prices. Ultimately, these storms can affect every part of a community, from homes and schools to businesses and essential services. Impacts remain after the storm has passed, such as unsafe roads, downed power lines, unsafe drinking water, and mold in homes.

How Hurricanes Are Changing with Climate Change

Although natural variability dominates year-to-year hurricane activity, observational and modeling evidence supports several climate-driven changes:

• Higher peak intensities and a greater proportion of major (Category 3–5) hurricanes as warmer sea-surface temperatures provide more energy for storm development.¹⁴
• Increased rainfall rates, consistent with the Clausius-Clapeyron relationship—warmer air holds roughly 7% more moisture per °C of warming—leading to heavier precipitation in tropical systems.¹⁵
• Higher storm surge due to rising sea levels, regardless of changes in storm intensity. The Mid-Atlantic experiences some of the highest rates of relative sea-level rise on the U.S. coast due to land subsidence, amplifying coastal flood risk from any given storm.¹⁶
• More frequent rapid intensification events, which complicate forecasting and emergency response and can leave coastal communities with less time to prepare, may be occurring.¹⁷

Projections remain uncertain for the total number of Atlantic storms and for changes in storm tracks. These uncertainties stem from the complex interplay between warming oceans, changes in vertical wind shear, Saharan dust transport, and large-scale atmospheric circulation patterns, as well as the limited resolution of global climate models for simulating individual storms. ¹⁸ Most climate models project a stable or slightly decreasing total number of tropical cyclones globally, but a higher proportion reaching major hurricane status, meaning the strongest, most damaging storms are likely to become more common even if overall storm counts do not rise.

For the Mid-Atlantic, the combination of intensifying storms, heavier rainfall, and rising seas suggests that future tropical systems are likely to produce greater impacts than comparable storms in the past, even without an increase in storm frequency.

Resources for Preparedness

• NWS Hurricane Safety Tips & Resources: weather.gov/safety/hurricane
• NWS Flood Safety: weather.gov/safety/flood
• NWS Tornado Safety: weather.gov/safety/tornado
• NHC Hurricane Preparedness Week: nhc.noaa.gov/prepare
• Ready.gov Hurricanes: ready.gov/hurricanes
• MARISA Climate Summaries: for additional regional context, including the Fall 2019 and Fall 2020 Chesapeake Bay Watershed Climate Impacts Summaries.