The pdf table below summarizes 20 years of weather data from National Weather Service Stations in Southeast Texas and some surrounding counties. It is based on winters rather than calendar years (unlike most reported data), reflects the last two decades rather than earlier ones, and attempts to reflect variation as well as what is typical. The chart provides for a specific station the percentage of the years the lowest winter temperature was above the number in the table; it also provides the percentage of the time the winter chill was at or below the range of numbers listed in the table.
Zone Summaries Revised Zone Summary
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By Year-Round Gardening
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Posted in Fruit Trees & Winter Weather in Southeast Texas, Weather & Climate
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Also tagged Austin, Chill hours Southeast Texas, Chill units in Texas, climate Houston landscaping drought, College Station, Galveston, Hardiness zones for Houston & Southeast Texas, Houston and Tropical Fruit, Houston fruit trees, Houston gardens, Houston weather climate websites, Lake Jackson, San Antonio, Southeast Texas Low Temperatures
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This 3 page file has my 2012 Winter Hardiness Zones for annual low temperature 1992-2012 in all National Weather Service Weather Stations with 10 years of data. The winter low temperature zones differ from USDA because the lows I am using are for the winter, not the calendar year. The way NWS reports things, a very cold last week in December and a very cold next week in January are treated as two different annual lows. Since we tend to swing from El Nino to La Nina events, this leads to very misleading data. As well, my tables use the last 20 years, rather than the 1975-2005 that the 2012 USDA model uses. Since 1975-1990 had some of the coldest days and months ever in the Houston area, this is not very helpful. As well, I take median average low temperatures at smaller intervals than 5-10 degrees. There is a big difference in fruit tree tolerances for mangoes between 28F and 25F. Lastly, I list chill zones for the area. These are not quite the same as the low temperatures since they are based on cool temperature duration more than a specific cold night. The last page is the USDA current zone map which is quite at odds with my data.
Randall Southeast Texas Low Temperature Zones
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The attached table in PDF represents a concise summary of annual low winter temperatures (October to April) for all official national weather stations in Southeast Texas for which there is 10 or more years of data since 1992. Most of them are for the full 20 years of data. The table lists weather stations first by Houston area locations (Harris County), followed by other sites in coastal and near-coastal counties bordering these (that is 0 and 1 county from the Gulf).
After this are other “interior” counties in Southeast Texas. For these, there are 2 or 3 counties that must be passed through to get to the coast. “County numbers to the coast” is a rough proxy for distance from the Gulf, and in rural areas is a very rough approximation of winter temperatures. The warmest areas generally are within a few miles of the Coast, and with some significant warmer exceptions for dense urban areas and Galveston Bay, temps get colder as you go inland. Lastly there is a a table of selected sites north or west of Southeast Texas. These are included to help interpret information about fruit tree performance in those areas, in order to use such information in Southeast Texas. For example, avocados that do well in Devine, Texas will likely do well in College Station south, because temperatures south of College Station are warmer than Devine, while north of College Station are typically colder, so would need increased protections.
The numbers in the cells represent temperatures F. If for example a cell has a temperature of say 28 in a column labeled 30% (as it does for Intercontinental Bush Airport), this means that 30% of the annual winter lowest temperatures during the last 20 years were at or above 28˚F. If you are considering planting a fruit tree that needs temperatures above 25˚(like a mango) , you can use this information, plus a comparison between your site and the nearest National Weather Station’s temperatures, to determine how much freeze protection a mango (or any other tropical or semi-tropical) would require.
Southeast Texas Winter Low Temps 1992-2012
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Year Round Gardening for Metro Houston 