< Previous Month Next Month >

San Marcos September Weather

Averages and records for weather in San Marcos, Texas in the month of September.

Typical San Marcos September Weather 1991–2020
Average daily high	90.7 °F
Average daily low	68.3 °F
Average monthly precipitation	4.1 inches
Average monthly snow	none
Daily chance of precipitation	24.2%
Daily chance of snow	0%

San Marcos September Weather Records 1893–2024
Highest temperature	111 °F	September 5, 2000
Lowest temperature	39 °F	September 28, 2010
Highest daily low	80 °F	September 1, 2020
Lowest daily high	61 °F	September 19, 1991
Hottest average high temperature	98.3 °F	2023
Coldest average high temperature	78.0 °F	1974
Most daily precipitation	8.0 inches	September 9, 1921
Most monthly precipitation	12.6 inches	1921
Most daily snow	none	-
Most monthly snow	none	-

Note: Daily averages are a moving average which includes 14 days before and after

Day	Average (°F)		Record (°F)
Day	High	Low	High	Low
September 1	94.3	71.7	105	52
September 2	94.1	71.6	105	60
September 3	93.8	71.5	106	52
September 4	93.6	71.3	110	50
September 5	93.4	71.1	111	51
September 6	93.2	70.9	105	51
September 7	92.9	70.8	105	52
September 8	92.7	70.5	106	54
September 9	92.3	70.3	103	51
September 10	92.0	70.0	104	55
September 11	91.8	69.7	102	54
September 12	91.6	69.4	102	53
September 13	91.4	69.1	102	50
September 14	91.1	68.8	102	50
September 15	90.8	68.5	101	51
September 16	90.6	68.1	100	51
September 17	90.3	67.7	100	51
September 18	90.1	67.5	100	50
September 19	89.8	67.2	103	45
September 20	89.6	66.9	102	45
September 21	89.3	66.7	103	50
September 22	89.1	66.5	105	42
September 23	88.9	66.1	102	43
September 24	88.7	65.8	102	45
September 25	88.4	65.5	103	47
September 26	88.1	65.1	103	46
September 27	87.8	64.8	101	42
September 28	87.5	64.4	101	39
September 29	87.3	64.1	99	42
September 30	87.1	63.9	98	42

Weather Station Details

Years	Station	Coordinates
1893–2024	San Marcos	location