Perigee data brief · NOAA observations
Where U.S. high-tide flooding grew fastest, 2000–2025
Among 71 NOAA gauges with complete comparison windows, Eagle Point, Galveston Bay, TX recorded the largest rise: from 4.2 minor-threshold flood days per year in 2000–2004 to 30.4 in 2021–2025—an average increase of 26.2 days per year. 60 of the 71 eligible gauges increased.
Analysis by Ryan Cardin · Published
Eligible NOAA gauges
71
Ten years at least 90% complete
Gauges that increased
60
47 at least doubled their five-year average
Median change
+4.6 days
Per year across all eligible gauges
The 10 largest increases in high-tide flood days
Bars compare average minor-threshold flood days per meteorological year. The ranking uses the absolute increase in days, not percentage growth.
| Rank | NOAA gauge | 2000–04 | 2021–25 | Increase |
|---|---|---|---|---|
| 1 | Eagle Point, Galveston Bay, TXNOAA 8771013 | 4.2 | 30.4 | +26.2 |
| 2 | Kawaihae, HINOAA 1617433 | 2.4 | 23.0 | +20.6 |
| 3 | Hilo, Hilo Bay, Kuhio Bay, HINOAA 1617760 | 7.6 | 24.4 | +16.8 |
| 4 | Kahului, Kahului Harbor, HINOAA 1615680 | 2.2 | 18.4 | +16.2 |
| 5 | Nawiliwili, HINOAA 1611400 | 3.0 | 16.8 | +13.8 |
| 6 | Trident Pier, Port Canaveral, FLNOAA 8721604 | 1.6 | 15.0 | +13.4 |
| 7 | Lewisetta, VANOAA 8635750 | 1.6 | 14.6 | +13.0 |
| 8 | Sewells Point, VANOAA 8638610 | 3.2 | 15.8 | +12.6 |
| 9 | Duck, NCNOAA 8651370 | 3.4 | 15.8 | +12.4 |
| 10 | Galveston Pier 21, TXNOAA 8771450 | 2.8 | 14.2 | +11.4 |
What the comparison shows
The increase is broad rather than confined to one coastline. The top ten span 5 states, while 60 of all 71 eligible gauges recorded a higher recent average. Hawaii contributes four of the top ten gauges; Atlantic and Gulf stations fill the other six.
The ranking is deliberately station-level. “Eagle Point” means the NOAA gauge on Galveston Bay, not every street or property in the surrounding metro. The repeated measurement at one fixed location is the strength of the comparison; treating it as a citywide impact map would overstate what the data proves.
View the complete 71-gauge ranking
Every row passed the same ten-year completeness screen. Negative values mean the recent five-year average was lower.
Methodology and limits
For every eligible U.S. coastal NOAA tide-prediction station, Perigee averaged the annual number of days exceeding NOAA's local minor high-tide-flood threshold across meteorological years 2000–2004 and again across 2021–2025. A meteorological year runs May through April. Every one of the 10 station-years used had at least 90% complete flood data. Stations are ranked by the absolute difference between the two five-year averages.
This is a gauge-level historical comparison, not a parcel-level flood-risk score or a causal model. NOAA thresholds are local, annual weather varies, and stations without complete records in both windows are excluded. A day above a moderate or major threshold also exceeds the minor threshold and is therefore included in the minor-threshold count.
The source is NOAA's State of High Tide Flooding and Annual Outlook and the official CO-OPS Derived Product API. NOAA defines the annual values as days exceeding each station's local flood threshold. This report uses the minor-threshold count, which includes days that also exceed moderate or major thresholds.
Reproducibility: the generator screened all 3,562 NOAA records returned for 2000–2025, applies one published filter, and keeps the ten annual observations behind every eligible result in the checked-in snapshot. The CSV includes the station IDs, coordinates, yearly counts, averages, change, and minimum completeness used in the ranking.
Questions about high-tide-flooding trends
- Where did high-tide flooding grow fastest from 2000 to 2025?
- Eagle Point, Galveston Bay, TX, had the largest increase among the 71 eligible NOAA gauges in this analysis. Its five-year average rose from 4.2 minor-threshold flood days per year in 2000–2004 to 30.4 in 2021–2025, an increase of 26.2 days per year.
- What is a high-tide flood day?
- In this report, it is a day when the observed maximum water level at a NOAA gauge exceeded that station's local minor high-tide-flooding threshold. Moderate and major exceedances also exceed the minor threshold and are included.
- Why compare five-year averages instead of single years?
- High-tide flooding varies with weather and ocean conditions from year to year. Averaging two five-year windows reduces the influence of one unusually quiet or active year while keeping the comparison understandable and reproducible.
- Does a station average describe every property in that city?
- No. A tide gauge records water at one location and NOAA's threshold describes local coastal flooding context. Street elevation, drainage, waves, rainfall, defenses, and distance from the gauge determine what an individual property experiences.
- What does meteorological year 2025 mean?
- NOAA's high-tide-flooding meteorological year runs from May through April. Meteorological year 2025 therefore covers May 2025 through April 2026.
Related Perigee research
Compare the observed flooding record with the 2026 U.S. king tide almanac, then read why a predicted astronomical high does not guarantee actual flooding in the king tide guide.