5 takeaways from this year's fall weather in Austin — and a look ahead to winter

Wednesday was not only the first day of December but also the start of meteorological winter, and Austin began the new season with daytime high temperatures about 10 degrees warmer than normal — which was on-brand for La Niña this year.

La Niña, or the cyclical cooling of the tropical waters in the eastern Pacific Ocean, tends to make seasons — like this year's fall and winter — drier and warmer in Central Texas. Here are five takeaways from this year's fall weather in Austin, with an eye on the wintry season ahead:

1. November contributed to a mostly dry autumn

Going into the final week of September, the first month of meteorological fall, Austin’s main weather station at Camp Mabry had measured only one-tenth of an inch of rainfall, according to the National Weather Service. The month was about to become the city's sixth-driest September in more than 120 years of record-keeping before overnight storms Sept. 28 delivered more than an inch and a half of rain, pushing the month's total to 1.79 inches. But even that amount was about 1.66 inches less than normal.

Monthly rainfall improved in October, which produced 5.3 inches at Camp Mabry — more than an inch above normal. But more than 20 of the month's 31 days were bone dry. Most of the rain was recorded over just five days, Oct. 10-14.

November's total rainfall amount of 2.4 inches came up about a half-inch short of normal. Only three days had measurable rainfall, and about 72% of the monthly total fell on one day, Nov. 3.

See forecasts: Live updates on Austin's weather

Thanks to September being Austin's ninth-warmest September on record — with an average temperature of 82.9 degrees — the average temperature for the three months of autumn this year was 72.9 degrees.

Last year, we experienced the 19th-warmest autumn in Austin, also courtesy of La Niña, with an average temperature of 72.1 degrees, or about 2 degrees above normal, for the months of September, October and November.

2. December already will be warmer than normal

The National Weather Service's outlook for the first week of winter calls for high temperatures more than 10 degrees warmer than normal and a small chance of rain.

Saturday could see patchy morning fog, but otherwise we should expect partly sunny skies with a high of 79. Clouds are likely to roll in at night, which should help keep evening temperatures above 63 degrees — only 3 degrees shy of the normal high for this time of year.

Austin on Sunday could get as warm as 78 degrees, but with more clouds and possible showers at night ahead of a cold front rolling through the region, forecasters said Friday.

"For Monday, expect a relatively strong cold front to push through quickly in the morning hours, with a few showers and potentially a thunderstorm possible ... mainly along and east of I-35 where deeper moisture will reside," the National Weather service said in a bulletin Friday. "A tenth of an inch of rainfall accumulation is probably about the best we can expect."

The workweek that will kick off Monday in Austin should have partly sunny skies with temperatures easing down to more seasonable levels, the weather service said.

"Breezy north winds and cooler daytime highs mainly in the 60s appear likely behind the front," forecasters said.

3. Drought conditions worsen, but not for us

You would think that the Austin area's largely rainless fall season should have meant a return to drought conditions. But that seems to be true only for the rest of the state.

This week, about 71.4% of Texas was abnormally dry or facing moderate to severe drought, according to the U.S. Drought Monitor. Three months ago, the week of Aug. 31, just before the start of meteorological fall, that proportion was only about 8.5%.

Recap: 5 things worth remembering about Austin's weather in 2020 — it was weirder than you think

Much of the Panhandle, West Texas and the northeast corner of Texas are seeing the worst conditions, with swaths experiencing severe drought typified by hard soils and elevated wildfire danger. But in Central Texas, the Austin metro area counties of Travis, Hays, Williamson, Bastrop and Caldwell remain drought-free.

You can get local drought updates sent automatically to your email inbox by signing up on drought.gov/drought-alerts/signup.

4. Hurricane season is over, thankfully

The annual Atlantic hurricane season, which can produce storms in the Gulf of Mexico that sometimes threaten Texas, ended Tuesday with no tropical cyclones formed in the month of November.

But the National Hurricane Center said the 2021 season was the third most active, with 21 named storms. For the seventh consecutive year, a tropical cyclone strong enough to earn a name formed before the official start of hurricane season June 1. The most recently named storm, Wanda, formed in October but had petered out by the first week of November.

Of the seven named storms that became hurricanes, four were major hurricanes, which have sustained winds of 110 mph or stronger.

"This compares to the long-term averages of 14 named storms, seven hurricanes, and three major hurricanes," the hurricane center said in its monthly summary.

Austin saw minimal effects from hurricanes this year, with only the slow-moving Hurricane Nicholas in mid-September skirting the Texas coast before making landfall north of Matagorda Bay and plodding into Louisiana.

A Pacific hurricane helped produce the rainiest day in Austin this year. In mid-October, the remnants of Hurricane Pamela, which made landfall on the Pacific coast of Mexico, merged with moisture produced by a slow-moving cold front from the northwest. Nearly half of the total rainfall that month fell on one day, Oct. 13, when 2.45 inches of rain made it the wettest day of 2021.

5. A La Niña winter is all but certain

When you hear forecasters talk about La Niña, they’re referring to the cooling of sea temperatures in the equatorial waters of the eastern Pacific Ocean. During a La Niña event, the cooler-than-normal ocean influences the pattern of the jet stream, a river of air that can corral or unleash cold air masses from the north.

The combination of these factors can affect weather in Texas. A La Niña at this time of year typically leaves Texas drier and warmer than normal because it tends to keep the jet stream and colder air pent up to the north.

According to the weather service's Climate Prediction Center, La Niña persisted in the tropical Pacific through the fall, and now forecasters say La Niña has a 90% chance of lasting through winter.

Forecasters have warned, though, that a La Niña winter doesn't rule out wintry weather in our region or guarantee it.

This article originally appeared on Austin American-Statesman: 5 takeaways from fall weather in Austin — and a look ahead to winter