One percent of the planet has experienced well below-average temperatures so far this year.

Meanwhile, 70 percent of Earth has had well above-average temperatures or record warmth.

This imbalance will likely intensify into 2027 with the potential for a record-breaking El Niño. Strong El Niño periods often appear as an upward stairstep in long-term plots of global temperatures — but this El Niño, because of its expected intensity, could be worth two stairsteps instead of one.

The record-breaking freight train of warmth that has crossed the undersea Pacific since April is now arriving on the shores of Peru, forming El Niño Costero.

That has caused summer-like temperatures in Lima, despite it being the start of winter, shares @hombredeltiempo 🧵 “The consequences are already being felt by the fishing sector due to the suspension of the industrial anchovy fishery, one of the largest fisheries in the world,” @hombredeltiempo said.

But this is just the start.

Catastrophic rainfall is possible later this year into next.

A remarkable 3.5˚C rise in central equatorial Pacific Ocean temperatures is possible by November, shows new ECMWF, which would mark the strongest El Niño on record.

Possible strength scenarios range from +2.8˚C to +4.3˚C, with sweeping consequences on global climate into 2027. Both the traditional and relative indices are forecast to break El Niño records, ECMWF shows.

This represents a notable strength increase compared to last month.

The event may peak in December — not November — meaning the projections here would keep rising for another month.

Breaking: The June ECMWF update has trended *even stronger* with this year's El Niño.

Almost every scenario now reaches past +3˚C, with a cluster of high-end scenarios in excess of +4˚C.

This outlook now depicts the strongest El Niño on record. The El Niño Costero outlook is also extreme, with scenarios generally ranging from +3˚C to +5˚C.

During the 1982-83 El Niño, the monthly Niño 1+2 Index peaked at +4.2˚C. In 1997-98, it reached +3.9˚C.

A freight train of warm water chugging beneath the surface of the Pacific Ocean is a big reason why a super El Niño may form this year.

Ocean waters have peaked around 7.5˚C (13.5˚F) above average, breaking records.

And now, it's nearing the western shores of South America 🧵 There are few modern comparisons to this big blob of warmth across the undersea Pacific — called a Kelvin wave.

Its intensity rivals what occurred at this time in 1997.

But there is more warm water available in 2026 that could further boost El Niño's eventual strength.

The notorious super El Niño of 1877-78 contributed to a global famine that wiped out 3 to 4 percent of the global population.

It was arguably the worst environmental disaster to ever befall humanity.

Are we better prepared now? The evidence says yes 🧵 There was no way to know that such a powerful El Niño was coming in 1877, nor what it meant.

Modern-day knowledge about the phenomenon was greatly boosted by advancements in climate monitoring and prediction following a super El Niño more than a century later in 1982-83.

New ECMWF data shows near a 100 percent chance of a super El Niño by October.

The central equatorial Pacific is forecast to surge 2.7˚C above average by then — approaching record levels — and this major climate event will still be intensifying 🧵 Potential El Niño strength scenarios range from +2.1˚C to +3.3˚C through October, according to 51 ECMWF ensemble members.

And warming will continue into December or so.

A strong-to-severe marine heat wave, which stretches more than 5,000 miles across the Pacific, is setting the West up for some volatile summer weather.

Elevated atmospheric moisture could cause unusual humidity, more monsoonal thunderstorms and higher tropical downpour risks 🧵 This marine heat wave and a developing El Niño are expected to increase the level of moisture availability around the West.

Possible impacts include elevated overnight temperatures, uncomfortably muggy conditions and higher risks for thunderstorms and tropical storm remnants.

Strongest El Niño on record this year?!

New ECMWF guidance shows a *75% chance of a super El Niño* by October, with some scenarios suggesting the most intense event in more than a century.

It will bring wide-reaching weather impacts that last into 2027 🧵 El Niño will raise the risk for droughts and downpours.

Droughts: India, Caribbean, central Africa, Indonesia, Australia, Philippines, South Pacific, Central America and northern Brazil.

Downpours: Peru, Ecuador, northern/eastern Africa, Middle East and the equatorial Pacific.

Have you ever heard of triplet cyclones?

This weekend and next week, three tropical cyclones may form in the West Pacific. One of them looks particularly powerful, near eastern Papua New Guinea.

🚨 Devastating rainfall of 50 to 100 inches may occur there as that storm stalls. ⚠️ Woodlark and Tagula Islands in eastern Papua New Guinea could spend *several days* near the center of a hurricane.

These extremely remote places could face a weather disaster over the next week as the storm feeds off of sea temperatures in the upper 80s in the Solomon Sea.

A super El Niño in 2026-27 wouldn't have the same impacts as events in 2015-16, 1997-98 and 1982-83.

Oceans have warmed substantially in recent decades, which can change the atmospheric response to El Niño's warm Pacific seas.

This should be kept in mind as planning begins 🧵 Harsh winds caused by El Niño probably won't be conducive to lots of Atlantic hurricanes, but it only takes one storm for it to be a memorable season.

Thoughts here from @AndyHazelton.

El Niño forming by May, potentially becoming strong by August — new ECMWF seasonal modeling.

By the numbers:

• 22% chance of a super El Niño by August
• 80% chance of a strong event
• 98% chance of a moderate event

That's according to data from 50 ensemble members. In the months ahead, there will continue to be weaker trade winds and more westerly wind bursts, allowing tropical Pacific waters to warm.

There have already been three formidable westerly wind bursts, shifting warm ocean water from west to east across the Pacific.

Copernicus Day for February has arrived.

How strong will El Niño get? What will it bring?

Let's find out 🧵 A moderate-strength El Niño is most likely to develop by summer.

This will have an upward influence on global temperatures, moisture availability and humidity — especially later in the year.

On a regional-to-local level, El Niño's impacts will vary.

The amount of water vapor pulsing across our skies set a record in 2024.

So far, 2025 is on pace to top that record.

A novel analysis in today's @washingtonpost, called floods above, dives deep into changing integrated vapor transport — and areas vulnerable to these changes 🧵 Integrated vapor transport (IVT) is a measure of moisture flowing across Earth's skies.

The level of moisture flow is increasing as the planet warms, combined with changes in wind patterns.

Copernicus Day for August has come and gone.

It marks a day when long-range forecast data for the months ahead gets released.

Here's what it shows! 🧵 A La Niña-like pattern will be in place as winter approaches.

Cool water in the Pacific affects climate patterns worldwide.

Marine heat waves in the mid-latitudes may lead to warm fall weather in parts of the United States, Europe and Asia.

There have been varying meteorological forces behind recent extreme rainfall events, but they are all connected by very unusual amounts of moisture pulsing above the United States.

Precipitable water, a measure of the total amount of water in the atmosphere, has been above the 90th percentile on half of all days so far this summer — the largest number of days to-date since records began in 1940. It's been above-average on all but five days.

Forecasters use precipitable water to gauge how much fuel is available for storms and how much rain can possibly fall. While it's not a one-to-one relationship, higher precipitable water brings a higher the chance for extreme rainfall — as long as there's a mechanism to squeeze the moisture out of the sky.

Globally, precipitable water reached record levels in 2024. So far, 2025 is a few notches below last year's record pace, but corridors of unusually high atmospheric moisture have developed near areas of much warmer than average oceans. This includes the central and eastern United States, Europe and eastern Asia.

Part of a meteorologist's job is to be an atmospheric detective — to understand and help others understand why certain things are happening.

Yes, it rains hard and sometimes floods during summer, but to understand what's driving this season's excessive rainfall is critically important. To dismiss it as 'just weather' is selling it short.

I think there's plenty of evidence to suggest that the trend toward a moister atmosphere is leaving an imprint on weather patterns in the United States this summer. Corridors of unusually high atmospheric moisture have developed near areas of much warmer than average oceans — which happen to be located near densely populated parts of the Northern Hemisphere.

Copernicus Day for July 2025 has arrived — a day when weather fans around the planet can learn about possible patterns in the months ahead.

Here's what the world can expect 🧵 A big global story is how warm the oceans are, especially in the Northern Hemisphere.

This may cause summer-like heat to last into fall and enhance downpours in many places.

Neither La Niña nor El Niño is currently active in the Pacific, but La Niña may return later this year.

June was more humid than average for a whopping 290 million people across 40 states.

Did it feel particularly sticky where you live?

New Mexico, Kentucky, Maryland, North Carolina and Ohio were the most unusually humid states.

🧵 on June Nights during June were very unusually warm.

Around 270 million people experienced above-average minimum temperatures. It was below-average for just 8 million people.

Overnight temperatures were most unusually high in Utah, Pennsylvania, New York, Vermont and Ohio.

Record-breaking humidity levels hit the Northeast and southern Canada on Monday, with dew points surging into the low-to-mid-80s.

Heat index values neared 115 degrees.

This illustrates that the current weather pattern exceeds typical summer weather.

Why it's so humid 🧵 Behind the extreme humidity is an air mass that took a winding, week-long, 4,000-mile journey northward from the Caribbean islands to the Northeast, bringing tropical weather to people that live far from the tropics.

Eyes will be on East Coast cities this week where temperatures will reach 100 degrees for several consecutive days, potentially breaking June records.

Around 40 million people may face triple digit heat 🧵 It could reach or exceed 100 degrees for up to five days in a row in some eastern areas this week.

For many places in the Northeast and Mid-Atlantic, the June record is at most two 100 degree days in a row.

Extreme humidity — not just extreme temperatures — will make headlines over the next week as a heat dome develops.

Humidity levels will surge across 40 states and southern Canada, bringing tropical rainforest-like conditions, especially next week 🧵 What feels humid to one person may not to another, so it’s important to recognize that the stickiness of the air is subjective.

This table describes the humidity level associated with dew point thresholds — and how each feels.