AUSTIN, Texas — After mid-April, Central Texas is over the springtime cold snaps and heads right into a warm, humid summer.
Warm daytime and nighttime temperatures and the usual influx of rainfall in the month of May make it the perfect time for mosquito populations to flourish.
Currently, Austin is already recording above-average precipitation for mid-May. And with a projected El Niño expected to organize in the coming weeks, rainfall may not be in short supply this summer.
Typically, El Niño events last for a long period of time. The picture below is a generalized setup of the conditions produced by El Niño across North America. Here in Texas during El Niño, we usually see wet conditions.
Increased rain and warm temperatures are two very large factors that boost mosquito breeding.
There is no definitive research on this subject, but there are some interesting coincidences when looking back at the strongest El Niño events of the past and mosquito-born illnesses in Texas.
During one of the strongest El Niño seasons on record between 2015 and 2016, Austin observed record-breaking rainfall in the spring and summer. Some of the highest monthly rainfall totals in May ever recorded were during this time – Camp Mabry at 17.59 inches and Austin-Bergstrom Airport at 13.44 inches in 2015. In 2016, the airport received an even higher monthly precipitation total for May, at 15.82 inches.
According to the World Health Organization, this record-setting rain was the same time as a worldwide Zika virus outbreak, a mosquito-borne disease, that largely affected South America but also the U.S. – including Texas.
There were 323 Zika cases reported in Texas between 2015-2016, including a couple in Bastrop and Burnet counties.
Another common mosquito-borne illness reported in Texas is West Nile virus.
You would expect high numbers for strong El Niño years if the link between mosquito-borne illness and El Niño summers were true. In 2015, Texas reported 275 cases and in 2016, 370 cases.
Those are not small numbers, but they are far below Texas's West Nile virus cases during the 2012 outbreak. In the summer of 2012, Texas reported 1,868 cases of West Nile virus. According to a 2013 report from the Center for Disease Control, Texas accounted for 33% of all West Nile virus cases that year.
But 2012 was not a strong El Niño year. On the contrary, North America was in the midst of a La Niña event, which normally causes drier, warmer conditions.
So while some links between mosquito problems and El Niño coincide quite remarkably, other events don't line up as well.
However, it is always good to be prepared against mosquito-borne illness. Here are ways you can protect yourself, ahead of this potentially wet summer.