2025 East Pacific Tropical Season Outlook
Jared Young

The East Pacific Hurricane Season is already in full swing for 2025. The official East Pacific Hurricane Season runs from 15 May through 30 November, with peak tropical activity falling between July and early September in this basin. Over the last 30 years, there have been an average of 15 named tropical cyclones, 8 hurricanes (Category 1-2) and 4 major (Category 3-5) hurricanes in the East Pacific annually. For the 2025 season, we are expecting a slightly below average season due to the current weak La Niña to Neutral condition of the El Niño Southern Oscillation (ENSO).

To obtain tropical development in a given region, the following “ingredients” have to be present:

1.  Low Vertical Wind Shear (minimal change in wind speed and direction with height)
2.  Warm Sea Surface Temperatures (greater than 26.5°C [80°F])
3.  High atmospheric mid-level moisture content

The current weak La Niña to Neutral ENSO status is expected to persist into at least Fall of 2025, and this is expected to produce slightly below average tropical activity in the East Pacific for the following reasons:

1. La Niña usually introduces overall cooler sea surface temperatures (SSTs) to the East Pacific Basin(waters east of 140W and north of the Equator). Current environmental conditions support this with cooler sea surface temperatures in place in East Pacific Waters between 140W and 90W. Cooler sea surface temperatures are hostile for tropical development by inhibiting convection within thunderstorms. 
2. While trade breezes typically weaken during La Niña conditions within the Atlantic Ocean, trade breezes across the East Pacific Ocean usually strengthen during these conditions. Stronger E’ly trade breezes against upper level W’ly breezes results in stronger vertical wind shear across the East Pacific, with this stronger vertical shear expected to “rip apart” tropical disturbances and prevent further tropical development of lows. 

 

    Figure 1: WRI's predicted storm totals for the 2025 East Pacific Tropical Season

When and where can we expect Tropical Development?

Tropical development usually originates east of 100W and north of 10N offshore the coastal waters between Mexico and Costa Rica, with systems tracking WNW’ward until reaching roughly 105-110W. Tropical cyclones will then usually either continue WNW’ward from this point or lift NNW’ward towards the Baja Peninsula and Sea of Cortez, weakening thereafter while entering cooler sea surface temperatures and stronger vertical wind shear within subtropical high pressure ridging offshore the W'rn United States. 

Sea surface temperatures east of 100W are currently slightly warmer than average and more suitable for tropical development, however. In instances where vertical wind shear weakens over these waters and the atmosphere has high amounts of moisture content suitable for deep convection, tropical development is still very possible. We have already seen this in the 2025 season with recent systems such as Tropical Storm Alvin, Hurricane Barbara and Tropical Storm Cosme, which were able to develop into named storms while meandering WNW’ward offshore Central America through this region of warmer sea surface temperatures. 

Figure 2: Tropical Storm Alvin offshore the coast of Oaxaca on May 30th, 2025. Picture courtesy of NOAA/NESDIS

WRI and our team of meteorologists will continue to work diligently to keep you updated of any tropical threats throughout the 2025 Eastern Pacific Hurricane Season. Clients who utilize WRI's customized forecasting services or subscribe to SeaWeather.net will receive complimentary tropical alerts and daily basin summaries for the East Pacific to ensure you and your crew, vessel, and clients stay safe throughout your summer itineraries. 

A New Look to Forecasts
Kyle Petroziello, Senior Meteorologist

WRI is happy to have introduced a modernized and cleaner look to our popular PDF forecasts this month. We are confident the updated look will allow for smoother understanding with better organization of material, graphics, and forecast tables.

Within the forecasts, notable features include:

• Section 1: A Voyage Summary with color categorized favorable, marginal, or unfavorable indicators for duration of winds/seas over a vessel’s weather constraints, as well as average ocean current factor.
• Section 2: A more focused Synopsis and Conclusions section highlighting large-scale weather features in play for your voyage, with an explanation of associated impacts and our recommendation reasoning to follow.
• Section 3: Graphics include a magnified view of the vessel’s route from departure or current position to arrival with wind barb indicators along the way under an updated map.
• Additional smaller graphics provided by SeaWeather (www.seaweather.net) of projected winds/seas, precipitation and mean sea level pressure, and ocean currents 24 hours from the time of forecast receipt.
• Section 4: A clear Route Recommendation highlighted above the Forecast Table.
• Forecast Table neatly separated by set 3 or 6 hourly time intervals over the vessel's expected position along your route, showing winds/seas with directions, periods, and any associated building or easing trends, sky conditions and visibility, and ocean current factor. 
• Links are provided at the bottom of each page, with easy openings to our Social Medias, to see further interactions from us.

Please click on each of the pages below to view a larger version.

We welcome all and any type of feedback on the new presentation style, as we continue to aim to tailor weather information in a style that best suits your needs. Please let us know to our email wri@wriwx.com.