After a rainy summer, La Niña conditions could bring a warmer, drier end to 2021

After a year of continued and unexpected changes, Texas' summer weather proved to be surprisingly calm, cool and collected.

While it was an exceptionally hot and dry summer for most of the country and the world, Texas tipped towards the cooler and wetter end of the spectrum. In fact, according to Texas + Water, July 2021 was recorded as the 21st coolest and 9th wettest July on record (for the past 127 years).

The unusually mild Texas summer left behind a relatively drought-free state with low drought percentages, an impressive feat.

At the beginning of August, only 9.3% of Texas was experiencing some level of drought, with about 6% of the Brazos River basin under a drought designation. And, like the previous month, August made the record books as the 9th wettest August in Texas over the past 127 years, according to the National Integrated Drought Information System

However, the fall and winter months may prove to be drier and warmer than normal. During September, rainfall in most of the state was 1 to 3 inches below normal, except for the upper and middle Gulf Coast, where 30-day precipitation was 4 to 8 inches above normal, much of which occurred during Hurricane Nicholas.

The Climate Prediction Center's seasonal outlook forecasts increased probabilities for below-normal rainfall and above-normal temperatures through the end of the year. According to state climatologist John Nielsen-Gammon, this is due to a projected return of La Niña conditions.

"Tropical Pacific sea surface temperatures are expected to continue cooling for the next several months, probably long enough so that a new La Niña event will be designated," Nielsen-Gammon said.

With that said, the Climate Prediction Center's Seasonal Drought Outlook shows that drought conditions will likely develop in most of Texas over the next several months.

This summer, the El Niño-Southern Oscillation (ENSO), a climate pattern of changing sea surface temperatures in the central and eastern tropical Pacific Ocean, was neutral. During the La Niña phase, the water temperatures are cooler, typically resulting in warmer and drier weather for Texas. During the El Niño climate pattern of ENSO, the water temperatures are warmer, supporting wetter weather in the U.S. Gulf Coast and Southeast. When ENSO conditions are neutral, the weather could tip in either direction.

Thankfully, it appears that this La Niña event will be weak, potentially ending by spring of 2022.

"There are some warmer subsurface temperatures that ought to be reaching the surface in a few months, so any La Niña is likely to be gone by early next year," Nielsen-Gammon said. "Thus, the most likely dry period is October through December."

The wet summertime conditions have been useful for the Brazos River Authority's reservoirs. Despite the predicted dry conditions going into fall and early winter, the Brazos River basin and BRA reservoirs are in relatively good shape heading into the colder seasons. As of October 7, 2021, the BRA water supply system was 97% full.

Even if dry conditions develop during the fall and early winter, reservoir levels typically stabilize during the fall months due to two main factors: shorter, cooler days that cause less evaporation and decreased water usage. Vegetation that requires watering goes dormant, and homeowners water their lawn and gardens less.

Despite the warm and dry conditions forecasted for this fall and early winter, Nielsen-Gammon states that the wildfires will remain relatively dormant for the Lone Star State.

"While a trend for drier conditions this fall is not necessarily good news, it probably won't pose too much of a fire threat," Nielsen-Gammon said. "Once we get past mid-October, temperatures rarely allow things to get bone-dry, and early fall is on average the least windy time of the year. Also, except for hurricanes, early fall usually has fairly light winds."

Another extreme weather event that has impacted the rest of the country has been the Atlantic hurricane season. While the season doesn't officially end until Nov. 30, Texas has mostly escaped major hurricane impacts.

"Hurricane activity in Texas usually tapers off by late September," Nielsen-Gammon said. "After that, it's hard to get a storm up to Texas without it curving off to the east."

Despite lowered chances of more hurricanes striking Texas, it's still important to stay prepared. Texans along the coast should know their hurricane risk, make an emergency plan with their family, build a disaster kit and connect with emergency notification systems. You can learn more about wireless emergency alerts here.

Understandably, extreme weather events taking place across the country can overwhelm and cause uncertainty. While you can't always know about major weather events in advance, Nielsen-Gammon says that "expecting the unexpected" can be a helpful mindset.

"Rare and extreme events are by definition something you can't rule out completely," he said. "You can expect them to happen eventually, just maybe not this year or the next. It was 32 years between our last extreme cold in 1989 and the extreme cold in 2021. We could see another next year, or just as easily have to wait several more decades."

To keep up to date with real-time data on rainfall, streamflow and reservoir elevations within the Brazos River basin, click here.