While we brace for the first freeze of 2012, I thought I'd take one last look back on 2011, a year which will go down in the Houston record book. Most of us will no doubt remember the horrendous heatwave last summer and the nearly year-long drought. Those two weather trends are the clear headlines; here are some specifics from the National Weather Service.
The average temperature in 2011 was 71.9°, which places last year in a tie for 1962 as the warmest year on record. Hobby's average temperature of 72.4° and College Station's 71.7° average make 2011 the warmest for those two locations. Galveston's 72.5° average temperature is a slim second to 2006's 72.6°. But its really interesting if you dig deeper into some of these numbers. The six-month period from March 1 to August 31 shows the core of the astonishing heat we felt. For all of the four major reporting sites, the average temperature in that time frame was at least a degree higher than the previous records.
We did see an uptick in rainfall for the last three months of 2011, but overall, it was an exceptionally dry year. Thanks to that little flourish at the end (Oct - 3.36", Nov - 4.70" and Dec - 4.28"), 2011 ended up with 24.57", making it the third driest year. Hobby's 25.41" for the year is the driest ever at that location. What was really telling was the six month period from March 1 to August 31. During that time each of the four major reporting sites saw their driest periods ever with less than 7" of rain recorded.
The big reason for the dry and warm conditions was the La Niña weather phenomenon. This cooling of equatorial Pacific waters shifts the jet stream so that storm systems are mainly diverted from moving toward Texas. This pattern is expected to continue for most of 2012, so we may be in for more of the same. You can read the complete stats for 2011 at kamala.cod.edu/tx/latest.nous44.KHGX.html.