By Billy Forney III
An update to my original post from December 14, 2018
Updated December 26, 2019

Have you ever wondered what type of weather we have experienced over the years on Christmas Day in Houston, Texas? The NWS Houston/Galveston Forecast Office has a great climate page dedicated to holiday climatology for Houston, including one for Christmas Day. I like creating additional visualizations of data, so this is my take on further explaining Christmas Day weather here in Houston.

Forecast
As you read the following, consider the forecast for Christmas Day 2019 in Houston currently calls for a low temp around 50 degrees and a high temp in the low 70s.

Summary of Climatology
The following is a summary of Christmas Day climatology for Houston, using data from the time period 1891 through 2018.

• Average temperatures: 62°F high, 44°F low
• Freezing temps have only occurred on 14 of the 128 Christmas Days since 1891
• The last time the temperature officially reached 32°F at KIAH on Christmas Day was in 2009. Temperatures that day ranged from a high of 49°F to a low of 32°F.
• 2015 (83°F) and 2016 (80°F) offered very warm Christmas Days, with high temps in the 80s. The only other instance where the high temp reached 80°F or higher was in 1964 (82°F).
• 1983 was quite cold: it was the last time that the high temperature failed to ascend to or above the freezing mark as the high that day only reached 28°F
• 1983 was also when the lowest temperature (11°F) was ever recorded on Christmas Day in Houston
• It has never officially snowed on Christmas Day in Houston, but we officially had a white Christmas in 1989 when a Trace of snow was recorded at both Houston’s Intercontinental Airport (KIAH) and Houston’s Hobby Airport (KHOU) from snowfall earlier in the week.

Christmas Day Normals

Christmas Day weather in Houston tends to be pleasant as the city’s average high temperature on December 25th is 63°F while the average low temperature is 43°F:

Short Term Look-back: Temperatures since the year 2000

Since the year 2000, Christmas Day in Houston has seen the following temperature ranges:

Interesting to note from Figure 2 that Houston’s temperatures on Christmas Day have reached the freezing mark only three times (2002, 2004, and 2009) since the year 2000.

Also interesting to note is the roller-coaster of a ride that temperatures have had when comparing one Christmas Day from the next in Houston. The following graph of the average of Christmas Day temperatures (calculated as the average of the high and low) since 2000 shows this roller-coaster ride quite well:

Last year, in 2018, the high temperature was 71°F and the low was 60°F for an average temperature that day of 65.5°F (see Figure 3). That followed a chilly 2017 (45°F). It just doesn’t feel like winter, or Christmas for that matter, without cold temperatures, at least cold for Houston standards. (Note: this year’s average temperature is currently forecast to be in the low 60s)

Longer-term look at temperatures 

Official temperature records for Houston go back to 1891. Since 1969, the official reporting station for Houston has been located at George Bush Intercontinental Airport (KIAH). Prior to that, various locations in Downtown Houston were the official reporting sites.

Since 1891, Houston’s warmest Christmas occurred in 2015 when the high temperature reached a record 83°F and the average temperature was a balmy 78.0°F. This average temp happened to be 25.0°F warmer than normal (normal high/low/average is currently 63°F/ 43°F/ 53.0°F). Conversely, the coldest Christmas occurred in 1983 when the average temperature was a frigid 19.5°F (33.5°F below normal). This year, the average temperature will be in the low 60s, about 10°F above normal, but won’t crack the top-10. Here are two tables showing the top 10 warmest and top 10 coldest Christmas days in Houston, based on average temperature readings:

Since the year 1891, Christmas Day in Houston has seen the following temperature ranges by year:

Figure 5 shows some interesting facts about temperatures in Houston on Christmas Day:

• The warmest Christmas Day in recent memory occurred in 2015 as the high temperature that day reached an uncomfortably warm 83°F. This set an official high temperature record for the date, according to the NWS Houston/Galveston website.
• The high temperature only managed to top out at 28°F in 1983, a record high for the date and the only time since 1891 that the high temperature failed to reach the freezing mark.
• The last time the low temperature reached the freezing mark was in 2009 when the high temp was 49°F and the low was 32°F.
• In the 128 years between 1891 and 2018, the high temperature has reached 80°F or higher just three times (1964, 2015, and 2016).
• In the 128 years between 1891 and 2018, the low temperature has reached 32°F or lower on only 14 occasions.

When looking at the average temperatures (average of high and low temps) grouped by temperature ranges, we have the following graph:

Figure 6 shows some interesting results:

• The average temperature has never been in the 80s or above (thank goodness!)
• The average temperature has only been in the 20s or below one time: in 1983, the average temp was 19.5°F with a high of 28°F and low of 11°F
• ~70% of the time, the average temperature will be either in the 40s or 50s (88 instances out of 128). This year, the average temp is expected to be in the 60s.

Other related graphics follow:

Houston has also seen some wild low-to-high, or “diurnal,” temperature swings on Christmas Day.  Since 1891, the simple average Christmas Day high temperature has been 61.6°F while the average low temperature has been 43.8°F (see figure 5).  This is an average diurnal temperature range of 17.8°F.  Often times, big temperature swings occur with a frontal passage that same day, as cold air takes over the warm, moist air that had been drawn into the system from the Gulf of Mexico in advance of the front.

In recent past, Christmas Day 2012 experienced quite a swing in temperatures as an arctic cold front moved through during the day.  After dressing for an outside temperature that topped out at 77°F early in the day, Houstonians quickly had to pack on the winter clothing as the temperature dropped 41 degrees to a low of 36°F later that evening. Here are the top 10 largest temperature swings on Christmas Day in Houston since 1891:

Snow 

It has never officially snowed on Christmas Day in Houston. However, a snow storm dumped 1.7″ of snow at KIAH and a Trace amount to KHOU on December 22, 1989. From that event, trace amounts of snow were observed on the ground and reported at both KIAH and KHOU for the next several days, including on Christmas Day 1989 for an official “White Christmas.” But, none of the wintry white stuff actually fell on the actual day.

Another snow event occurred on December 22, 1929 when 2.5″ of snow fell in Houston, according to the NWS Houston website. Areas further north of Houston, such as Crockett, TX and Groveton, TX, received up to 10″ in the 1929 event. But, again, nothing actually fell on Christmas Day with that event.

In more recent memory, many residents of southeast Texas remember the Christmas Snow of 2004 as areas south and southwest of Houston received up to 12.0″ of snow on Christmas Eve of that year. Snow totals were very impressive, as noted in this NWS event page and pasted below:

Sources and References

• National Weather Service (NWS) Forecast Office Houston/Galveston, https://www.weather.gov/hgx/ 
• National Centers for Environmental Information (NCEI), https://www.ncei.noaa.gov/
• References to data from 1891 through and including 1968 come from observations at Houston WB City, TX (WBAN: 12945, NWS Coop Number: 414305) which has the most complete data back to 1891 for the Houston area
• References to data from 1969 through and including 2018 come from observations at George Bush Intercontinental Airport Houston (Station ID: KIAH)

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