With weather systems moving from the Southwest U.S. to the northern Great Plains, more rainfall was able to efficiently form over the western part of South Central Texas in September 2004. Wetter and cooler than usual conditons for September came to the western part of South Central Texas, with Del Rio receiving 3.96 inches of rain. September 2004 ended up drier than normal for September over the eastern part of the area. At Austin Bergstrom, September 2004 was the 9th driest of record. After several cool fronts in August, the frequency of cool fronts slowed down some in September; however, one strong early September cold front moved across the area on September 6th. This cold front brought some unusally cool early morning lows on the 7th, 8th and 9th. After the 9th, warmer than usual September weather came from the 10th to the 24th. The warmest part of the month at Austin and San Antonio came the 11th to the 19th, while at Del Rio the warmest September days were from the 12th to the 17th. Even though fall began on the 22nd, warm days continued, although moderated from where there were in mid September. Several days of showers and a cool front moderated daytime temperatures after the 24th. Del Rio picked up 1.98 inches of rain on the 26th. Drier and warm weather came at the end of the month on the 29th and 30th.

On September 1st, showers and thunderstorms produced locally heavy rains over the western part of South Central Texas. Clouds and rain kept daytime highs very moderated for September 1st. The high of 76 at Del Rio was a record lowest daily high temperatures for September 1st at Del Rio. By September 3rd, partly cloudy conditions turned into a cloudier picture by the afternoon as widely scattered showers moved in from the south and southeast. This was followed by the weekend of September 4th and 5th to Monday the 6th, where scattered showers and thunderstorms picked up, ahead of a strong frontal system that passed over the area Monday, September 6th. This brought an increase in shower and thunserstorm acitviity during the day of Monday the 6th. The thunderstorm acitivity moved south of the area in the late afternoon through the evening and night of the 6th and early morning of Tuesday the 7th.

Dry early September weather prevailed the 7th through the 9th. Cool early morning lows were observed on the 7th, 8th, and 9th, in wake of the September 6th cool front. Lows across the Texas Hill Country were in the 40s and 50s on the 8th, and in the 50s on the 9th. Del Rio had a record low for September 8th of 57, and a record low for September 9th of 58. Austin Bergstrom had a record low for September 8th of 58.

By Friday the 10th, a few isolated showers showed up over the eastern part of the area, and the same pattern continued the 11th. Afternoon highs continued to warm into the mid 90s by the 11th. The warm weather continued into the week of September 13 to 17, briefly interrupted by rain and showers. Even though the week of September 19 to 25 brought the first day of Fall on the 22nd, summer like condtions prevailed through the 22nd, 23rd, and 24th. Conditions then began to slowly moderate as a weak cool front came through the area the night of the 24th, and the remnants of Ivan passed southeast of the area, helping to bring clouds and areas of rain, with showers and isolated thunderstorms. A developing low over the Southwest U.S. and West Texas help to bring clouds and rains to the west part of the area on the 26th, and to most of the area by the 27th. Del Rio picked up 1.98 inches of rain on the 26th.

September ended with dry and warm weather on the 29th and 30th, although moisture began to rise quickly during the day of the 30th, ahead of a rain making weather system coming into the Southwest U.S.

The average September temperature was 80.5 degrees, 1.1 degrees above normal. The average high was 90.5, and the average low was 70.5. Heating degree days 0 and cooling degree days 472. The highest temperature reached 95 on the 12th and 16th. The lowest was 64 on the 30th. Highest wind gust was 31 mph from the southeast on the 13th and from the southwest on the 22nd, with showers and thunderstorms in the area. Rainfall was 1.92 inches, 1.08 inches below normal. Rainfall from January 1st to September 30th, 2004... 26.32 inches or 1.80 inches above normal.