The Eastern Pacific continues to be very active. This is very typical for this time of year – and especially in seasons like this one, with an El Niño event strengthening – and with record-setting sea-surface temperatures, the activity is not expected to stop anytime soon. After Genevieve, the next named storm will be Hernan. This will likely happen this week, as the National Hurricane Center has already designated a system located a little over 1,000 miles east-southeast of Honolulu, Hawaii, as Potential Tropical Cyclone One-C.
PTC 1-C is expected to strengthen throughout the rest of this week, and it will likely be named Hernan by Friday at the latest. The estimated minimum central pressure at 11 a.m. EDT Wednesday was 1003 mb, or 29.62 inches of mercury. Heavy rainfall is expected to begin on the Big Island on Friday and move into Maui by the beginning of the weekend, continuing to impact much of the rest of the Hawaiian Islands throughout the weekend. There’s the potential for rainfall totals between 5 and 10 inches across much of the island chain, but some spots could accumulate up to 20 inches.
These amounts could cause life-threatening flooding and mudslides, especially across mountainous areas. It is not possible to pinpoint which locations will receive the highest rainfall totals, so residents and visitors are encouraged to monitor the system closely as it inches closer in the coming days.
Along with the rain bands, there could also be some gusty winds, which could knock down trees and power lines. However, the biggest threat from this system will be the heavy rainfall and the potential for life-threatening flooding and mudslides. PTC 1-C is predicted by NHC to be a strong tropical storm as it moves over or near Hawaii, in line with most model guidance, and landfall as a hurricane is not out of the question.
The NOAA Historical Hurricanes Tracks database shows that only two named storms have made landfall on the island of Hawaii at tropical storm strength (see Fig. 2 below):
- Darby (2013) peaked as a Category 3 hurricane but made landfall with top sustained winds of just 40 mph (64 km/hr)
- Iselle (2014), the island’s strongest landfall on record, peaked offshore at Cat 4 strength but made landfall with top sustained winds of 60 mph (97 km/hr)
The most recent tropical cyclone to directly impact the main Hawaiian Islands was Hurricane Hone in August 2024. Hone passed within about 50 miles (80 km) south of South Point on the Big Island on August 25, 2024, while strengthening into a Category 1 hurricane. Although its center did not make landfall, its outer bands directly affected the Big Island.
A busy Eastern Pacific season is in progress
The Eastern Pacific has had a very active season so far. There have been seven named systems in this region, and according to climatology, the eighth named system typically forms by August 21. With Hernan likely becoming a named tropical system by the end of this week, the Eastern Pacific season would be running about nine days ahead of schedule. Two of the seven named storms in the Eastern Pacific have become hurricanes: Fausto and Genevieve.
The Eastern Pacific basin, on average, has several peaks in activity. For hurricanes and tropical storms, we are currently in the first peak of the season. The second peak usually occurs around the beginning of September, and the third peak occurs toward the end of September.
Although the Eastern Pacific has been active, only one tropical system, Tropical Storm Boris, has made landfall in Mexico, doing so in June 2026. Hurricane Fausto traveled far from the Eastern Pacific into the Central Pacific, where it encountered dry air and cooler waters, weakening by the end of July.
Farther west, over the northwestern Pacific Ocean, Tropical Depression 16W, also known as Nangka, and another tropical depression, 13W, continue to move over the open waters while riding along a large ridge of high pressure. Both storms are expected to continue moving northeast, staying away from land as they gradually weaken into remnant lows through the end of this week.
Tropical Storm Cristobal is born, well away from land
Just shy of 10 days behind schedule, the Atlantic basin has its third named tropical system of the season. Tropical Storm Cristobal formed from the trough that exited the United States. Cristobal is moving east at about 25 mph, and it’s not expected to keep its tropical characteristics for longer than 24 hours. The system will likely become a remnant by Thursday afternoon. Tropical Storm Cristobal is not only moving away from the United States over the open waters of the Atlantic, but it’s also moving over cooler waters, which will likely make the system short-lived.
Farther south, we continue to monitor two tropical waves. The first one, labeled Invest 92L — as designated by the NHC when a system doesn’t meet the full tropical characteristics, like a well-defined center and sustained winds, but is monitored closely enough to link it to weather models — has a high chance (80% chance) of tropical development during the next 48 hours. If the system develops and stays as a depression, tropical storm, or even a weak Category 1 hurricane, it will likely continue moving along the trade winds into the Caribbean. This could be good news because, although it would be a tropical system, it is likely to bring rounds of showers that would be greatly beneficial for the Caribbean islands, which are currently experiencing extreme drought and even water shortages in places such as Puerto Rico. If the system strengthens further, it would likely curve and either brush the Lesser Antilles or come close while remaining on the Atlantic side.
Behind this tropical system, there’s another tropical wave that has emerged from Africa. This tropical wave does not have an “Invest” label yet, although this could change as the system acquires better characteristics and environmental conditions become more favorable for it to become a tropical depression early next week. This one is located a few hundred miles south of the Cabo Verde Islands and is still very disorganized. During the next week, the system will continue to move west over the tropical Atlantic, and it could move into an area more favorable for development into a tropical depression or tropical storm.
At the moment, none of the tropical systems we’re monitoring in the Atlantic represent a threat to the United States. In fact, even if those two waves enter or come closer to the Caribbean, they will likely struggle to survive. Vertical wind shear is currently very strong over this area, continuing to range between 30 and 50 knots over the central Caribbean and portions just north of the central Caribbean islands. These conditions are very consistent with the strong El Niño now in progress.
Bob Henson and Jeff Masters contributed to this post.
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