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Hurricane Maria (2017)

Category 4 winds devastated Puerto Rico. Restoring electricity to all customers whose buildings were safe to reconnect took 11 months; researchers estimated 2,975 excess deaths over six months.

Last updated September 7, 2026

Hurricane Maria struck Puerto Rico on September 20, 2017, with sustained winds of 155 mph (250 km/h). The NHC estimates $90 billion in damage in Puerto Rico and the U.S. Virgin Islands, in 2017 dollars.1 Power restoration proceeded over months; reaching all customers whose buildings were safe to reconnect took about 11 months.2 Researchers estimated 2,975 excess deaths in Puerto Rico from September 2017 through February 2018, a figure later adopted by the territorial government.3

Satellite image of Hurricane Maria making landfall in Puerto Rico on September 20, 2017
Hurricane Maria making landfall in Puerto Rico as a high-end Category 4, September 20, 2017. Credit: NOAA / CIRA · Public domain

Meteorological History

Maria became a tropical depression on September 16, 2017, east of the Lesser Antilles. It reached Category 5 before striking Dominica on September 19 UTC, then reached its peak of 175 mph (280 km/h) and 908 mb around 0300 UTC September 20, south of St. Croix. An eyewall replacement cycle weakened it to Category 4 before its Puerto Rico landfall.1

Landfall and Destruction

Maria made landfall on September 20 near Yabucoa, Puerto Rico, as a Category 4 hurricane.1 The eyewall directly crossed the island from southeast to northwest, bringing destructive winds and flooding across Puerto Rico, with storm surge affecting exposed coasts. Wind damage was widespread and catastrophic: roofs were completely removed from structures, vegetation was stripped bare, and transmission towers were toppled. Severe as that wind damage was, the aftermath is what defined Maria.

A structure collapsed over a basketball court in Cayey, Puerto Rico after Hurricane Maria
A collapsed structure in Cayey: Maria's winds stripped roofs and flattened buildings across the island. Credit: NIST · Public domain

Infrastructure Collapse & the Power Crisis

Maria severely damaged the electricity system operated by PREPA, a public utility already facing financial and maintenance problems. The grid lost power island-wide. Restoration was gradual, so the 11-month completion time does not mean every household remained without electricity for that entire period.2

Satellite night-lights of Puerto Rico before and after Hurricane Maria, showing the island gone dark
Puerto Rico's night lights before and after Maria: the island-wide grid collapse was the longest blackout in U.S. history. Credit: NOAA NESDIS · Public domain

The loss of electricity disrupted water supplies, communications, healthcare, and food storage. GAO documents the logistical difficulties of restoring the grid and the need to strengthen it against future disasters.2

Human Toll & Excess Mortality

Puerto Rico initially reported 64 deaths. The GWU study estimated 2,975 excess deaths between September 2017 and February 2018, with a 95% confidence interval of 2,658–3,290 under its preferred population-displacement model. The government subsequently adopted the estimate.31

An excess-mortality estimate compares observed deaths with the deaths expected without the disaster. It captures a broader burden than an initial count of individually attributed deaths, but does not establish the specific cause of every additional death.

The study found elevated mortality among older men and residents of poorer municipalities. It does not support attributing almost all excess deaths to the power outage alone.3

A resident of Barranquitas, Puerto Rico receives food and water weeks after Hurricane Maria
A resident of Barranquitas receives food and water weeks after Maria, as relief slowly reached remote inland towns. Credit: U.S. Air Force / Tech. Sgt. Larry Reid Jr. · Public domain

Economic Impact & Long-Term Recovery

The NHC’s $90 billion damage estimate covers Puerto Rico and the U.S. Virgin Islands and is expressed in 2017 dollars. Its stated uncertainty range is $65–115 billion.1 This is a damage estimate, not a measure of all subsequent economic losses.

Workers repairing the electrical grid on Vieques, Puerto Rico after Hurricane Maria
Crews repair the grid on Vieques: restoring service to all customers whose buildings were safe to reconnect took 11 months. Credit: Western Area Power / Jeff Miller · CC BY 2.0

GAO’s review describes damaged infrastructure, difficult terrain, material shortages, and coordination problems during restoration. PREPA was publicly owned; describing it as a private utility at the time of Maria is incorrect.2

The estimated death toll includes both direct and indirect effects; the NHC says they could not reliably be separated for this event.1 See government aid after a hurricane for disaster assistance and economic ripple effects for the wider consequences.

Sources

  1. National Hurricane Center. (2019). Tropical Cyclone Report: Hurricane Maria (AL152017). NOAA. https://www.nhc.noaa.gov/data/tcr/AL152017_Maria.pdf ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  2. U.S. Government Accountability Office. (2019). Puerto Rico Electricity Grid Recovery. https://www.gao.gov/products/gao-19-296 ↩ ↩2 ↩3 ↩4

  3. Milken Institute School of Public Health, George Washington University. (2018). Ascertainment of the Estimated Excess Mortality from Hurricane María in Puerto Rico. https://research.gwu.edu/gw-researchers-2975-excess-deaths-linked-hurricane-maria ↩ ↩2 ↩3

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