What To Know About The 'Blob' Heatwave Blanketing The Pacific From Japan To America

Travelers, be warned: The "blob" weather pattern has returned, not to be confused with the 1958 cult-classic horror movie. This marine heatwave in the Pacific Ocean is now stretching about 5,000 miles from Japan to the West Coast of the United States. An oceanic phenomenon first detected more than a decade ago and exacerbated by global warming, these "blobs" of warm water are helping smash temperature records, not in a positive way. Already known for muggy, uncomfortable summers, Japan experienced its hottest summer ever in 2025, setting a new temperature record of 107.2 degrees Fahrenheit on August 5.

Unpacking weather terminology can be a head-scratcher for the layperson. How did the blob enter our lexicon? Its first appearance, from 2013 to 2015, was an area of persistent high pressure off the North American coast that led to ocean temperatures increasing by a whopping 7 degrees above normal. A second blob followed in 2019. The latest iteration — officially named NEP25A — first materialized in May 2025, growing to 3.1 million square miles by July and representing one of the top three largest marine heatwaves in the northeast Pacific Ocean since monitoring began in 1982.

When this high pressure doesn't budge, winds decrease, which in turn prevents cool water from rising from the ocean depths to bring down temperatures. Marine scientists are concerned about the blob's potential future impacts on the ecosystem, as aquatic life is still recovering from the 2015 event. Sea lions were exposed to toxic algae and weathered food shortages. Clamming shut down, crab hauls plummeted due to low-oxygen conditions, and the die-off of common murre seabirds set a record. Meanwhile, land conditions aren't much better. Californians are dealing with higher humidity levels and seeking relief at beaches, as increased moisture levels could potentially decimate mountain snowpack conditions this winter.

What can such a weather event mean for your vacation? When the world is dealing with blobs and even the urban heat island effect, you don't necessarily need to cancel a trip, but do take some precautions. Let's face it: Nobody wants to miss out on a trip to Japan these days, which is in high demand, earning accolades as the ultimate destination for solo travelers and the most popular country for repeat visits. Instead, think about seeking air-conditioned havens like museums and malls, and break up your sightseeing adventures with cafe stops for boba or iced matcha lattes. Staying hydrated and cool is key to avoiding heat stroke, so pack parasols and portable fans. Invest in a wardrobe with breathable and moisture-wicking fabrics, and consider dress codes when packing, as some destinations may have modesty rules or cultural norms.

The good news is that experts believe this heat wave will ease near the West Coast as we head into winter, a time when many seek the warmth of a Hawaiian vacation or Mexican cruise. Still, the lesson here is that weather patterns will have a greater influence on how we plan for recreation and how the places we enjoy recreating at will withstand environmental threats, such as those faced by the five most endangered national parks in America. Michael McPhaden, a senior scientist at the National Oceanic and Atmospheric Administration, told CNN, "The fingerprint of climate change is clearly evident in what is transpiring now in the North Pacific" because it has warmed at the fastest rate of any ocean basin over the last 10 years. So, when planning for that special vacation, incorporate weather conditions into your research, along with tips for top restaurants and beaches.