monthly climate summary

While little relief from drought was found in September, the reprieve from the intense summer heat was nearly instantaneous. After three summer-like days to begin the month, fall weather kicked into high gear and temperatures plummeted. The hottest summer in Oklahoma history soon gave way to the 30th coolest September since records began in 1895. The statewide average temperature for the month was 70.9 degrees according to preliminary data from the Oklahoma Mesonet, 1.6 degrees below normal. Unfortunately, similarly good news did not arrive for most of drought-stricken Oklahoma.

To get a sense of the state’s legendary heat waves of its past, Oklahoma’s youngest generation would normally turn to the stories of parents, grandparents or great-grandparents. Tales of those summers from the 1930s, 1950s and even 1980 seemed as dated as rotary phones or changing the television channel by hand. They will no longer need to ask older generations about harsh summers, however. They now have their own stories to tell, and theirs will be from the hottest of them all – the summer of 2011.

Fueled by exceptional drought and a seemingly impenetrable heat-dome, July roared through Oklahoma’s legendary heat waves of the past to become the state’s hottest calendar month on record. According to data from the Oklahoma Mesonet, the July statewide average temperature finished 7.5 degrees above normal at 89.1 degrees, smashing the previous record of 88.1 degrees set back in July 1954. Statewide averages date back to 1895. The news was equally grim on the rainfall side of the ledger.

The meager amount of rain that managed to fall on Oklahoma during June was no match for the extreme heat and wind that was so prevalent for much of the month. The statewide average rainfall total for June was 1.17 inches, more than 3 inches below normal and the fourth driest June on record dating back to 1895. Southwestern Oklahoma suffered through its driest June on record with an average of 0.52 inches. Add heat to the equation and you have the ingredients for drought intensification. That is exactly what occurred during what became the second warmest June on record.

Even though severe weather only struck on a few days during May, those instances gave the month more than its money’s worth. The most violent weather occurred on May 24 when several long-track violent tornadoes tore their way through Oklahoma from west to east. While the exact details of the twisters are still being discovered, their 10 confirmed fatalities are unfortunately all too certain. Those casualties make the month the deadliest due to tornadoes in Oklahoma since May 1999.

Warm and dry weather grabbed the headlines as the record-setting extremes of February gave way to a downright dull March. Data from the Oklahoma Mesonet ranked the month as the eighth driest and 31st warmest March since records began in 1895. Severe weather was scarce, although a few reports of large hail and high winds accompanied the few thunderstorms that did occur. Elevated fire risk was common during the month, a result of the dry and windy conditions.

In a state accustomed to extreme weather, February was a bit startling to even the most seasoned veteran of Mother Nature’s whimsy. The roller coaster ride began on the month’s first day with a crippling blizzard and ended on its last with tornado warnings. The month was peppered with records, including the state’s all-time lowest minimum temperature and greatest 24-hour snowfall total. Those extremes occurred amidst the larger backdrop of an intensifying drought across the western two-thirds of the state. 

December tried to end 2010 in a tranquil manner after a year’s worth of tumultuous weather. Mother Nature provided a punctuation mark instead as a strong tornado touched down near Westville in Adair County on New Year’s Eve. The tornado eventually traveled into Arkansas, killing three near the small town of Cincinnati. A less violent hazard – drought – dug its heels into most of the state during the month as lack of precipitation contributed to the 32nd driest December since records began in 1895.

The mild and dry weather Oklahoma experienced through the first two months of fall continued into November, thanks in large part to La Nina’s influence. The climate phenomenon, signaled by cooler-than-normal waters in the equatorial pacific and global disruptions of weather patterns, brings an increased chance for mild and dry weather throughout the southern one-third of the United States, included Oklahoma. The effects of La Nina are reflected in the state’s temperature and rainfall statistics for the three months of climatological fall, September-November. 

Dry and warm conditions continued over much of the state, although a late-month drink gave a bit of relief to drought-plagued southwestern Oklahoma. A powerful upper-level storm that brought significant rains to the southwestern quarter of the state kept this October from finishing as one of the state’s top-ten driest on record. Despite that moisture, however, much of the state still received a meager 20-60 percent of normal rainfall for the month.