The Texas Legislature passed
HB 1150 in 2015, which allows for the sale of fireworks before certain holidays which include San Jacinto Day, Texas Independence Day, Memorial Day, July 4th and New Years Day.
[snip]
BE IT ENACTED BY THE LEGISLATURE OF THE STATE OF TEXAS:
SECTION 1. Section 2154.202(g), Occupations Code, is amended to read as follows:
(g) A retail fireworks permit holder may sell fireworks only to the public, and only during periods:
(1) beginning February 25 and ending at midnight on March 2;
(2) beginning April 16 and ending at midnight on April 21;
(3) beginning the Wednesday before the last Monday in May and ending at midnight on the last Monday in May;
(4) beginning June 24 and ending at midnight on July 4;
(5) beginning December 20 and ending at midnight on January 1 of the following year;
[/snip]
The additional sales dates have to be approved by the commissioners court, there is is more about drought conditions not being in effect, and locations closer than 100 miles to the Mexican border can also sell for Cinco de Mayo.