In Part I of this series we took a look at the rainfall and temperature data from the Big Bend in West Texas. In Part II we looked at the weather data from South Texas. In the final part of this series we will look at the weather data from the Texas Hill Country. For the purposes of this article, Texas Hill Country will refer to the Llano Uplift region, which includes Llano County and parts of Mason County, San Saba County, Blanco County, and Burnet County.
As in Part II, the weather data from the 2010 bluebonnet season will be used as the benchmark for best possible conditions, and is presented alongside the current data. In addition, the data from 2012 is also presented for comparison purposes. Again, the data presented in the table below came from a different source than that of the departure from normal rainfall maps.
Totals throughout the fall were below average, but rainfall in January (and February, not shown) has picked up and been above average. Temperatures during seed germination were mostly below average, but I don't believe this is cause for concern. I do think the above average temperatures during December and January (especially) are a little troubling. January was recently reported as the fifth warmest on record in the United States, which doesn't bode well for the vernalization process.
Seed germination period
Bluebonnet seed germination occurs from sometime in September to sometime in November and requires average to above average rainfall as well as warm temperatures for best results.
Rainfall throughout the Texas Hill Country was one to three inches below average in September 2019.
October 2019, perhaps the most important month for rainfall, saw a range of values. Llano County and Burnet County were mostly below average (anywhere from a half to two inches). Much of Mason County and southwestern San Saba County, however, were at or above average, which is very good news.
Rainfall in November 2019 was again anywhere from a half inch to two inches below average in Burnet County and most of Llano County. Southern and northeastern Mason County saw about average rainfall.
Rosette development period
By this point all bluebonnet seed that is going to germinate will have germinated and the plants are developing a root structure and going through vernalization. Though temperatures were warmer than average during December and January that doesn't necessarily mean that they were too warm for vernalization, however, the data from the 2010 bluebonnet season indicates that cooler than average temperatures are optimal.
December 2019 rainfall was a half inch to two inches below average across the Texas Hill Country.
January 2020 saw a reversal of the dry trend of the previous fall. Most of Llano County was a half inch to two inches above average, most of southern San Saba County was half inch to two inches above average, and most of Mason County was average to a half inch above average.
At the time of this writing the February 2020 rainfall data is not available, however, I feel confident that most of the Texas Hill Country will again be above average for rainfall, based on totals recorded on a private ranch in north central San Saba County. Those totals show rainfall an inch and a half above average with a week left in February.
2020 Texas Hill Country bluebonnet forecast
At the beginning of 2020 I was pretty down on the chances for a good bluebonnet bloom in the Texas Hill Country. But after seeing the January and February data, and especially after comparing it to the 2012 rainfall data, I feel much better about our chances. 2012 was a very good year for Texas bluebonnets in the Texas Hill Country, and if you look closely, you will see a pattern that is somewhat similar to this year. The most important difference is that 2012 had above average rainfall in October 2011. But if you look at the totals from October 2019 in the chart at the top of this page you will see that even though they are below average they aren't significantly below average, and the departure from normal maps show many areas with average to above average rainfall. That fact, combined with the above average rainfall in January and February have me thinking that we will see an average year in spots (primarily the western half of the Llano Uplift) with some bright spots here and there. The most promising area, based on the rainfall map data, appears to be southern Mason County.
Merlo, J. (2020, January 11). Contributing factors for a bluebonnet bloom (Part I). Retrieved from https://www.jasonmerlo.com/gallery/contributing-factors-bluebonnet-bloom-texas/
Merlo, J. (2020, January 12). Contributing factors for a bluebonnet bloom (Part IV): Texas Hill Country. Retrieved from https://www.jasonmerlo.com/gallery/contributing-factors-bluebonnet-bloom-texas-hill-country/
NOAA. (n.d.). Advanced Hydrologic Prediction Service. Retrieved from https://water.weather.gov/precip/#
NOAA. (n.d.). Climate at a Glance. Retrieved from https://www.ncdc.noaa.gov/cag/county/mapping
NOAA. (2020, February 6). January 2020 was 5th warmest on record for the U.S. Retrieved February 11, 2020, from https://www.noaa.gov/news/january-2020-was-5th-warmest-on-record-for-us
Vernalization. (2019, December 17). Retrieved from https://en.wikipedia.org/wiki/Vernalization