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Record-breaking May rainfall in Texas and Oklahoma, by the numbers

The wettest May on record for Texas and Oklahoma has come to a close as the states continue to fight the floods. The final tallies from the month-long deluge are as extreme as they are improbable, topping previous rainfall records by absurd amounts.

The torrential May rains were deadly for the states, where at least 31 people have died in storms just since Memorial Day weekend, the Associated Press reports. At least 10 people remain missing.’s Jonathan Erdman calculated that the National Weather Service offices across Oklahoma and Texas issued a combined total of 594 flash flood warnings in the month of May, which was 97 more than all of last year. At least three of those warnings have been flash flood emergencies, which are only issued in the most life-threatening flooding situations.

The final rainfall totals and the records they broke were enormous.

A few exceptional records set across Texas include:

Statewide — Wettest month on record (8.81 inches)
Dallas-Forth Worth — Wettest May on record (16.96 inches)
Dallas Fort-Worth — Second wettest spring (March-May, 25.05 inches)
Wichita Falls — Wettest month on record (17 inches)
Childress — Wettest month on record (13.21 inches)

May rainfall totals of 15 to 20 inches are widespread across Texas. According to the office of the Texas state climatologist, the month of May is now the wettest on record for Texas, having received an average of 8.81 inches statewide. The rest of the top 5 records are all within less than a ¼-inch of each other, with May 2015 blowing away the previous record by over two inches.

[Houston drone video reveals extent of major flooding]

Texas statewide wettest months:
1. May 2015 (8.81 inches)
2. June 2004 (6.66 inches)
3. May 1914 (6.62 inches)
4. September 1936 (6.55 inches)
5. May 1929 (6.45 inches)

The National Weather Service in Forth Worth calculated that Texas-wide May rains amounted to over 35 trillion gallons, an amount that would cover the entire state in water eight inches deep.

Looking at the water that flowed into Texas reservoirs alone — a tremendous 8 million acre-feet — would be enough to meet New York City’s water needs for seven years, according to The Washington Post’s Wonkblog. And that’s just a fraction of what has actually fallen from the saturated skies over the past month. NBC in Dallas-Forth Worth says that what actually fell would be enough to supply the world’s population with drinking water for over 27 years.

Exceptional records set in Oklahoma:

Statewide — Wettest month on record (14.40 inches)
Oklahoma City — Wettest month on record (19.48 inches)
Lawton — Wettest month on record (20.47 inches)

Oklahoma also set a new statewide record for wettest month, besting the previous by an unbelievable 3.65 inches. “The rains began the first week of May and by the end of the month the state had seen the most rainfall on record for any month in its history,” writes Gary McManus, the Oklahoma state climatologist. “The statewide average, as measured by the Oklahoma Mesonet, finished at 14.40 inches, 9.58 inches above normal.”

[May rainfall busted the Texas drought. Big time.]

The previous record wettest month for Oklahoma was October 1941, when an average of 10.75 inches of rain fell across the state. To put this month into perspective, these are the kinds of long-term records that are usually broken by less than an inch, and rarely do they pull ahead by more than that.

Nearly 30 inches of rain fell across southeast Oklahoma over the past 30 days. Oklahoma City got off to a very wet start on May 6, when severe storms lingered over the metro area spawning tornadoes and triggering deadly flash flooding. Oklahoma City ended the month of May with 19.48 inches, making it the wettest month out of any month, and surpassing the previous record by a mind-boggling five inches.

[May rains super-charged by strengthening climate patterns]

South of Oklahoma City, Norman received 23.39 inches of rain in May, according to the Oklahoma Mesonet, compared with its average of 4.76 inches. The wettest station in the mesonet over the past 30 days was located in Atoka County, where 28.17 inches of rain was recorded — more than the past four years combined at the station.

Though the floods have been devastating and deadly, they have also brought much-needed rain to a region stricken by extreme drought over the past few years. As of Thursday, the U.S. Drought Monitor says that no part of Texas or Oklahoma are in severe drought. In fall 2011, nearly 80 percent of the states were in exceptional drought — the most severe on the drought scale.

Fortunately for the Southern states, the pattern has taken a turn toward dry and should remain that way for the next few days. However, the Climate Prediction Center’s one- and three-month outlook call for wetter-than-average conditions across the South and Southeast as El Niño builds, which means Texas and Oklahoma might not be out of the woods just yet.

More Texas-Oklahoma flood coverage:

May rainfall busted the Texas drought. Big time.

Houston drone video reveals extent of major flooding

May rains super-charged by strengthening climate patterns

May 6: Oklahoma City sets record for wettest day in May

May 14: Two days of torrential rain cause flooding nightmare in Houston

May 24: Oklahoma City sets record for wettest May

May 26: Houston is under water (again)

A previous version of this story listed May as the wettest month on record for Dallas-Fort Worth. It was the wettest May on record, and the third wettest month overall.