An analysis of the historical occurrence of freezing temperatures in Brownsville, Texas

[Sabal_Louisiana]

I am intrigued that such a southerly location might experience temperatures below freezing so I set set out to see just how often they occur there and if any trends are taking place..

The station used for official climatological data is at Brownsville/South Padre Island Intl. Airport located at 25.9146, -97.4231,  20 ft. above m.s.l., a few miles east of city center.

It is representative of the typical meteorological conditions of the local area.

Primarily,  let's focus on the period 2000-2024, with data for the period easily available in tabular form from the NWS Brownsville webpage.

The average annual minimum temperature for this nearly 25 year period is 33F. (assuming the 29 deg F temperature experienced in Jan 2024 is likely to be the lowest of the calendar year). This is the same for both the calendar year and by winter (Nov.-Mar.) The average annual lowest minimum temperature by month for this period is 36F. 

Therefore, we can say with some confidence that the Brownsville area lies within cold hardiness zone 10A.

Of the past 25 winters, 12 years (48%)  have had temperatures fall to 32 or lower and 11 (44%) winter seasons have done so.

The longest span of years without freezing temperatures was 2005-2008, when the temperature got no lower than 35f. This was immediately followed by the longest stretch of years with at least one day below freezing,  2009-2011; also three years.

The lowest temperature during the period was during the great freeze of Feb. 2021 when the temperature hit 22f. This was the only instance during the 24+ years that hard freeze criteria was met. The second lowest was with  2 years. 27f in December 2023.

The average annual minimum temperature for 2000-2009 and 2010-2019 was 33f for each decade but for 2020-2024 it has been 30f, with freezes 3 of the 5 years.

 

 

 

[Jimbean]

I've looked at Brownsville data before and noticed bigger swings in extremes.  If I remember correctly, the all time record low was 12F.  I concluded that Brownsville was roughly on par with Orlando and according to the way I define zones in Florida, would be on the high side of 9B.

[Xerarch]

Brownsville is quite an interesting anomaly in the world, look at that location! Just under 26 degrees latitude, low elevation, near the coast.  Just about anywhere else in the world fitting that criteria would scarcely or never experience a freeze at all, let alone hard freezes or temps in the teens.  Having said that, Brownsville's average temps are warm year round and hard freezes are rare, and there are a lot of great tropicals growing all over town.  Even 2021 didn't do in all the Royals and various other zone 10 species.

[SubTropicRay]

15 hours ago, Jimbean said:

I've looked at Brownsville data before and noticed bigger swings in extremes.  If I remember correctly, the all time record low was 12F.  I concluded that Brownsville was roughly on par with Orlando and according to the way I define zones in Florida, would be on the high side of 9B.

Brownsville's 12F all time low illustrates it is much more susceptible to greater cold anomalies than Orlando.   

[Austinpalm]

On 2/20/2024 at 8:04 AM, SubTropicRay said:

Brownsville's 12F all time low illustrates it is much more susceptible to greater cold anomalies than Orlando.   

So true.....

The Great Plains just serve to funnel the cold air down here sometimes.  Florida's extreme southeasterly location coupled with whatever interference the Appalachians provide along with having generally warm water on three sides really serves to protect it more than similar latitudes in Texas. Furthermore, all the waterbodies across Florida give it an additional level of moderation not seen anywhere in Texas except possibly the extreme southeast portion (Houston to Port Arthur area).  And that is nowhere near Brownsville. But we are able to maintain a solid zone 10a and even 10b average in places for good stretches.  Unfortunately, one 8b/9a winter can do more damage than four or five 10a/10b winters in a row can make right.  So our gardens will rarely ever look like a Florida garden in a comparable zone.  In addition to our on average more frequent arctic intrusions, we also average about 20 inches less rainfall.  Anyways, every part of the world has some challenge to creating a personal garden paradise.  If the occasional cold front is the worst of my issues,  then I'm good with it.

[RFun]

On 2/20/2024 at 9:04 AM, SubTropicRay said:

Brownsville's 12F all time low illustrates it is much more susceptible to greater cold anomalies than Orlando.   

Yes, but despite that, the people there are certainly not living in fear of trying many different species of plants/palms.  Certainly, the length of cold spells being very short is always a help.  You are also talking about a palm growing area where they know how to take care of their palms (if needed).  Lots of knowledge around.

Edited February 23, 2024 by RFun

[SeanK]

A hard freeze is understood to be 28°F.

No doubt, there is more palm expertise in the greater Orlando area than there is is Brownsville.

[RFun]

On 2/23/2024 at 9:34 PM, SeanK said:

A hard freeze is understood to be 28°F.

No doubt, there is more palm expertise in the greater Orlando area than there is is Brownsville.

A hard freeze isn't just 28F.  It's really spending around at least 2 or more hours at 28F or less to qualify in any kind of practical way.  And palm expertise between those locations is going to be pretty similar, if I had to guess.  Brownsville growers do have more experience with colder temperatures.  Food for thought.

Edited February 28, 2024 by RFun

[richtrav]

A couple of years ago I did a regression analysis to see if any warming has occurred since the 19th century (it has). Brownsville is an ideal place to do it in South Texas since records go back to 1878 and the location since the 1940s has been at the airport, away from the central urban heat island. It shows the average annual minimum was about 28 in the late 1800s and has risen to above 32 today. You can also see the outliers of 2021, 1983 and 1962, and the two extreme outliers of 1989 and 1899. The farthest back records go is to 1847 albeit with many interruptions.

 

[richtrav]

On 2/19/2024 at 4:32 PM, Jimbean said:

I've looked at Brownsville data before and noticed bigger swings in extremes.  If I remember correctly, the all time record low was 12F.  I concluded that Brownsville was roughly on par with Orlando and according to the way I define zones in Florida, would be on the high side of 9B.

You have to realize our area does not have large moderating bodies of water except at the coast. For instance look at how cold it gets at the Archbold station in SW Florida, I believe their record low is 13F. Not coastal and no big lakes nearby. In 1899 a minimum of 20 was recorded at Port Isabel where a radiational freeze did not occur.

The 1989 freeze was so extreme it dropped temperatures into the teens south of the Tropic of Cancer in Tamaulipas on Dec 24, but again it was a radiational event.