Tides on the Texas Coast: Semi-Diurnal, Twice Daily

The Texas Gulf Coast experiences **semi-diurnal tides**—**two high tides and two low tides every 24 hours 50 minutes** (lunar day).

Tidal Pattern Details

• Type: Semi-diurnal (mixed, slightly unequal highs/lows).
• Cycle: ~12 hrs 25 min between successive high tides.
• Range: Typically **0.5–1.5 ft (0.15–0.45 m)** – microtidal. Small compared to East Coast (6–10 ft) or Bay of Fundy (50 ft).
• Spring Tides (New/Full Moon): Range up to 2 ft.
• Neap Tides (Quarter Moons): Range <0.5 ft – barely perceptible.

Key Locations & Variations

Drivers of Variation

• Wind: Strong onshore (SE) winds pile water up (+1–2 ft); offshore (N) winds blow water out (-1 ft). **Meteorological tides often exceed astronomical.**
• Pressure: Low pressure = higher water (inverse barometer).
• River Discharge: Mississippi/Atchafalaya plume, Trinity, Brazos, Colorado rivers affect salinity/levels locally.
• Loop Current / Eddies: Gulf mesoscale features raise/lower mean sea level 6–12 in seasonally.
• Hurricanes: Storm surge (feet to 20+ ft) – entirely different mechanism.

Practical Implications

• Fishing: Moving water (tidal flow) triggers feeding. Best: 2 hrs before/after high/low. Wind-driven flow often matters more.
• Boating/Shallow Draft: Know your draft + tide + wind. 1 ft tide = access to flats/back lakes.
• Coastal Flooding: Nuisance flooding (high tide + onshore wind) increasing with sea-level rise (~4 mm/yr TX coast).
• Data Sources: NOAA Tides & Currents (tidesandcurrents.noaa.gov), Texas Coastal Ocean Observation Network (TCOON), Windy, PredictWind.

Texas tides are **small but consequential**—wind rules the day, moon sets the baseline. Always check wind forecast alongside tide tables.