Puerto Rico is a tropical island located between the Caribbean Sea and the North Atlantic Ocean. With this in mind, Puerto Rico is frequently hit by intense flooding that is linked to heavy rains from tropical storms and hurricanes. Puerto Rico gets a high amount of rainfall, especially in the northern and central areas, ranging from 3,000 to 4,300 millimeterseach year. A study shows that about 8% to 10% of the population is currently at risk of flooding from hurricane-related rainfall that occurs as often as every five years.
On April 28, 2025, severe flooding in Puerto Rico turned deadly when a man lost his life after attempting to drive through high water in a heavily flooded area of San Juan, where some areas saw nearly nine inches of rainfall. In a separate incident in Bayamón, six individuals visiting a waterfall were swept away by sudden floodwaters and had to be rescued. These recent flooding incidents are just one of many that have impacted Puerto Rico over the years.
The Role of Climate Change
Climate change is making Puerto Rico’s flooding problem worse. A report from the U.S. Environmental Protection Agency says the commonwealth has warmed by over 1°F since the mid-1900s, while surrounding water temperatures have increased by almost 2°F since 1901. These rising temperatures contribute to more intense hurricanes and heavier rainfall.
Since 1958, Puerto Rico has seen a 33% increase in rainfall during heavy storms, and experts believe this trend will continue. Stronger rainstorms mean rivers are more likely to overflow, and low-lying areas may flood more often as water takes longer to drain away.
Furthermore, rising sea level is another concern. Since 1960, the sea level along Puerto Rico’s coast has risen by roughly four inches and is expected to increase by one to three feet in the next century. As sea levels rise, coastal areas become increasingly vulnerable to flooding, particularly during storm surges caused by hurricanes.
Flood Zones in Puerto Rico
Across Puerto Rico, certain communities sit in the path of rising waters. These flood zones, officially mapped by the Federal Emergency Management Agency (FEMA) through the Flood Insurance Rate Map (FIRM), help identify where flooding is most likely to occur.
Flood-prone areas are categorized by the level of risk, and the distribution of these zones tells us how widespread the flooding threat is.
- X Zone / 0.2% shaded (62.9%) – Areas with a 0.2% chance of flood occurring each year (500-year flood). Though these areas are considered moderate to low risk, the potential for flooding remains.
- AE Zone (31.5%) – Areas identified using specific, detailed methods, with base flood elevations provided to estimate flood water heights.
- A Zone (4.7%) – Areas identified through approximate methods, without specific base flood elevations. These regions are still considered flood-prone, but their flood risks are less defined.
- VE Zone (0.9%) – Coastal areas with a high risk of flooding, where base flood elevations are provided. These zones face not only flooding but also strong wave action.
In the Estuario de la Bahía de San Juan basin, flood risks are a significant concern. Some municipalities are more vulnerable than others, as shown by the percentage of their land located in flood zones:
| City/Municipality | Flood-Prone Area |
| Carolina | 14.6% |
| Loíza | 11.7% |
| San Juan | 10.6% |
| Cataño | 4.73% |
| Guaynabo | 1.46% |
Puerto Rico Flood History
With Puerto Rico clearly at risk, it’s worth noting that the island has already experienced numerous severe floods over the years, including:
1960 Eastern Puerto Rico Floods
On September 6, 1960, eastern Puerto Rico was devastated by one of the worst floods in recorded history. Following the passage of Hurricane Donna, heavy rains began to fall around 9 p.m. on September 5 and dropped more than 10 inches of rain across the region.
Every river basin from Rio Grande de Manatí eastward was flooded. The flood claimed 117 lives, left 30 people missing, and injured 136 others. Additionally, over 3,600 homes were damaged, with 484 completely destroyed. Total damage exceeded $7 million.
October 5-10 1970 Floods
A slow-moving tropical depression brought days of rain across Puerto Rico, totaling nearly 40 inches in just six days. The heavy rainfall caused widespread flooding, with San Juan being particularly affected, where bridges were washed out, homes flooded, and roads closed due to landslides.
The six-day flooding resulted in 18 lives lost, 34 people missing, and 10,000 residents left homeless. The destruction amounted to $65 million, with agriculture alone suffering $8 million in losses. President Nixon declared Puerto Rico a disaster area, marking this as one of the worst floods in the island’s history.
1992 Three Kings Flash Floods
On January 4, 1992, a large area of low pressure was sitting off the east coast of the United States, with a cold front stretching from the Bahamas down to Hispaniola. By the next day, the front had moved across the Dominican Republic, causing strong thunderstorms over Puerto Rico. This combined weather system brought heavy rainfall to the island, with up to 20 inches in just one day.
The floods caused widespread damage across Puerto Rico, affecting at least 40 municipalities. The worst flooding occurred along the Río de la Plata and Río Grande de Patillas. Other towns like Salinas and Ponce also experienced severe flooding. In total, the floods caused more than $150 million in damage, claimed 23 lives, injured 167 people, and left thousands of homes damaged or destroyed.
Mitigating Flood Risks
With the serious effects of flooding in Puerto Rico, it is very clear that action needs to be taken to reduce future risks. Fortunately, there are ongoing efforts to address the problem. The Federal Emergency Management Agency has committed nearly $4.6 million to projects aimed at improving drainage systems across various university facilities and other sectors in Jayuya and Vega Alta.
In addition, FEMA is working on large-scale projects to enhance the island’s resilience to natural disasters. FEMA has allocated nearly $35 million for initiatives like the rehabilitation of the San Juan Bay National Estuary and $39 million for the restoration of coral reef barriers to reduce flooding risks.
Moreover, FEMA has allocated nearly $32 billion for more than 10,900 projects to rebuild and improve infrastructure through the Public Assistance Program after Hurricane María, a Category 4 storm that devastated the island in September 2017 and claimed the lives of 64 people. Many of these projects focused on hazard mitigation.
Additionally, the agency has committed over $3 billion to 198 Hazard Mitigation Grant Program (HMGP) projects to strengthen Puerto Rico’s ability to withstand future weather events.
Moving Forward with Flood Resilience
With tragic loss of life, damaged homes, and disrupted communities, flooding has left a lasting impact on Puerto Rico and its people. Given the island’s history of devastating floods, it’s clear that they are no longer rare events but rather they are becoming a part of life.
But there is hope. Ongoing efforts to rebuild and reduce risk show that Puerto Rico is moving in the right direction.
Still, the danger is far from over. As storms grow stronger and seas continue to rise, the need for action becomes more urgent. Investing in planning, infrastructure, and awareness is important and will determine the island’s ability to weather the next flood.