El Niño intensifies to very strong levels, but reservoir relief will take time

Since the National Oceanic and Atmospheric Administration (NOAA) announced that we had officially entered El Niño conditions in June, little has changed in water supply reservoir levels in the Brazos River Basin.

The entire Brazos River Basin has experienced drought conditions since mid-summer, and water supply reservoir levels have declined. However, some areas of the basin have shown signs of improvement.

While some areas of the basin received several inches of rain, others experienced none. But that is expected to change.

According to John Nielsen-Gammon, Texas State Climatologist and director of the Southern Regional Climate Center at Texas A&M University, “The forecast of El Niño is as solid as it gets. Partly that's because it's already here, in spades.”

NOAA’s National Weather Service Climate Prediction Center reports that El Niño conditions in the Brazos River Basin are strengthening, with a strong-to-very strong El Niño likely through January-March 2027.

Some meteorologists and news outlets refer to this El Niño as a “super” El Niño; however, NOAA classifies El Niño/La Niña conditions as weak, moderate, strong, and very strong.

“The natural climate cycle has been strengthening at a breakneck pace since it was first declared in June and is stronger now than it’s ever been on this date. And isn’t done bulking up yet,” reports Mary Gilbert, a Cable News Network (CNN) meteorologist.

This time a year ago, a weak La Niña, El Niño’s cool counterpart, was in place, and only a handful of other years have seen such a rapid flip to a potent El Niño, including some of the strongest events on record, which include 1982-1983, 1997-1998, and 2015-2016.

According to NOAA, during an El Niño year, winter temperatures tend to be cooler and wetter than usual for the southern tier of the U.S., which can lead to increased flooding. However, in a La Niña year, winter temperatures tend to be warmer and drier than normal in the south.

While predictions indicate what someone expects to happen in the future, weather predictions are data-driven analyses. The Relative Oceanic Niño Index (RONI) records cold and warm periods and shows historical El Niño/La Niña episodes from 1950 to the present.

The latest weekly RONI value has reached over 2.0 degrees Celsius (3.6 degrees Fahrenheit) above average. This meets the “very strong” threshold, the highest official category forecasters use. It’s also when El Niño gets its unofficial “super” moniker.

Along with RONI, weather forecasters use the Pacific Decadal Oscillation (PDO), a recurring pattern of ocean-atmosphere climate variability that spans decades.

The PDO shifts between warm (positive) and cool (negative) phases along much longer timescales (every 2 to 3 decades). El Niño events tend to be stronger during positive (warm) PDO phases and weaker during negative (cooler) ones. In simple terms, a positive PDO can greatly intensify an El Niño. The PDO has remained in a cool (negative) phase since around 2000, so it remains to be seen how the PDO may impact this very strong El Niño event.

A side-effect of a strengthening El Niño this year was a delayed start to hurricane season. According to AccuWeather, hurricane Isaias broke the 121-year record as the Atlantic’s latest first hurricane, arriving at 11:30 p.m. on October 7, 2026. That ended the longest wait for the first hurricane since record-keeping began in the 1800s.

AccuWeather experts are forecasting up to two additional hurricanes before the Atlantic hurricane season ends on November 30th.

Neilsen-Gammon explains, “If sea surface temperature anomalies in the tropical Pacific stopped intensifying tomorrow, we'd still have a strong El Niño this winter. It is forecasted to peak in December, but that could be a month off either way.”

He predicts that El Niño will “be weakening by early spring, and we might be dealing with its opposite, a La Niña, by this time next year.”

What does all this mean for the Brazos River Basin?

Chris Higgins, BRA’s lead hydrologist, says, “Any additional rainfall will be welcome considering most of the Brazos River Basin has continued to experience below-normal rainfall since late spring.”

Some reservoirs in the Brazos River Basin have declined amid worsening drought conditions. Higgins assures that, “Although we’ve been experiencing ongoing drought conditions, the BRA water supply system of 11 reservoirs remains in good condition at 89 percent full, storing about 1.7 million acre-feet.”

Does this mean we’ll see immediate results from rising reservoir levels?

No. When drought conditions persist, it may take a little longer to see reservoir improvements once rain arrives. The ground must first absorb enough moisture to become saturated enough to generate runoff, increased flow in rivers and streams, and ultimately increased storage in reservoirs.

“The consequences of all this rain will be a progression over the season: first soil moisture in the ground is replenished, then storms start producing as much runoff as water soaking into the ground, then it's mostly runoff,” says Neilson-Gammon. “Reservoirs show little improvement at first but then respond increasingly well to each successive rainstorm.”

Nielson-Gammon states, “It's extremely likely that overall, from October through April, the Brazos River drainage will receive above-normal precipitation amounts on average.”

“There's almost as much chance of record-breaking rain as there is a chance that rain will be below normal. Temperatures will probably tend to be on the cool side too, with a greater than normal chance of snow,” Nielson-Gammon said.

Higgins added, “We’re currently in one of the wetter periods of the year, so above-normal rainfall could provide some meaningful improvements in drought coverage and help replenish reservoir storage.”

“However, while a strong El Niño increases the likelihood of wetter conditions, there’s no certainty that this weather pattern will bring additional rainfall,” Higgins said. “Any relief from drought conditions ultimately will depend on the distribution, magnitude, duration, and intensity of rainfall received.”

While a very strong El Niño is lining up to deliver some long‑awaited moisture, the Brazos Basin won’t refill overnight.

Remember, soil must soak, streams must flow, and storms must repeat before we see real change.