Weather

Climate

The climate at Amistad is semi-arid in moisture and subtropical in temperature. Humidity is more often high than low, with periodic morning fog. Summers are long, hot, and frequently humid; winters are mild and vary between sunny, warm, cloudy, and cool weather.

Nearly 80% of the annual precipitation occurs from April through October. During this period, rainfall is mainly in the form of thunderstorms and heavy downpours often resulting in flash flooding. The small amount of precipitation for November through March usually falls as steady light rain or drizzle. Average annual rainfall is near 19 inches. Rainfall extremes vary from 4.34 inches in 1956 to 37.75 inches in 1914.

Over the course of a year, the temperature at Amistad typically varies from 40°F to 98°F and is rarely below 31°F or above 102°F. The hot season lasts from May 24 to September 10 with an average daily high above 91°F. The hottest day of the year is August 11 with an average high of 98°F. The cold season lasts from November 24 to February 17 with an average daily high below 70°F. The coldest day of the year is January 1 with an average low of 40°F and high of 65°F.

Historical Lake Level Data

Text only description of image: The graph shows Lake Amistad’s water surface elevation from 1968 to February 23, 2023. The vertical axis of the graph shows elevation from 1020 feet (311 meters) to 1150 feet (351 meters) with designations made at 10-foot intervals. The horizontal axis represents the years from 1968 to 2023 with designations made every 2 years.

Elevations demarcated on the graph: Lowest Outlet at 283.5 meters, Spillway Crest at 1086.4 feet (331 meters), Conservation Pool Elevation at 1117 feet (340.46 meters), Bottom of Spillway Gates at Full Open at 345.64 meters, Top of Flood Control Pool at 347.59 meters, Top of Super Storage Pool at 348.78 meters, Bottom of Spillway Bridge Beams at 349.58 meters, Lowest Known Embankment Settlement Point at 350.79 meters, Bottom of Spillway Bridge at 350.95 meters.

Approximate Water Level Every Two Years

1968 – 1020 feet

1970 – 1070 feet

1972 – 1100 feet

1974 – 1121 feet

1976 – 1118 feet

1978 – 1112 feet

1980 – 1116 feet

1982 – 1121 feet

1984 – 1115 feet

1986 – 1112 feet

1988 – 1119 feet

1990 – 1115 feet

1992 – 1124 feet

1994 – 1110 feet

1996 – 1075 feet

1998 – 1084 feet

2000 – 1081 feet

2002 – 1067 feet

2004 – 1086 feet

2006 – 1110 feet

2008 – 1109 feet

2010 – 1115 feet

2012 – 1108 feet

2014 – 1082 feet

2016 – 1093 feet

2018 – 1087 feet

2020 – 1070 feet

2022 – 1069 feet

Noted Historic Levels

September 22, 1974 – 1135.66 feet

July 6, 2010 – 1129.86 feet

May 2013 – (Historic Low) 1055.9 feet

August 15, 2022 – (Historic Low) 1052.44 feet

July 17, 2024 – (New Historic Low Reached) 1,047.15 feet

Storage at Conservation (in Thousand Cubic Meters)

1964 – 1980: 4,174,100 TCM

1981 – 1992: 4,173, 900 TCM

1993 – 2004: 3,883,160 TCM

2005 – 2018: 4,036,250 TCM

(Decreases in water storage capacity due to silt accumulation.)

(Increases in storage capacity due to consolidation of silt during drought.)