Read values and identify information directly from a real NOAA tide graph.
Line graph titled Verified Water Level at Sewells Point, VA — October 21, 2025 — NOAA/NOS/CO-OPS Station 8638610.
The horizontal axis shows the time of day in 24-hour format, from 00:00 (midnight) to 23:00 (11 PM), with labels at every 4 hours. The vertical axis is labeled Verified Water Level (ft) and ranges from 0 to 4.0 feet in increments of 0.5 feet.
The line begins at approximately 2.98 feet at midnight. It rises to a first peak of about 3.3 feet between 01:00 and 02:00, then falls steadily to a low of approximately 0.76 feet around 07:00–08:00. The line then rises again to a second peak of about 3.3 feet between 13:00 and 14:00. After this peak it falls again, reaching the lowest point of the day — approximately 0.66 feet — around 20:00, before beginning to rise again toward 1.74 feet by 23:00.
The graph shows two clear high tides and two low tides over the course of the day, a pattern called a semidiurnal tide. Both high tides reach approximately 3.3 feet and both low tides reach approximately 0.7 feet.
Tides are the regular rise and fall of sea level caused by the gravitational pull of the Moon and the Sun on Earth's oceans. As the Moon orbits Earth, its gravity pulls ocean water toward it, creating a bulge of water — a high tide. On the opposite side of Earth, another high tide forms. As Earth rotates, different locations pass through these bulges, causing tides to rise and fall roughly twice a day.
The graph shows verified water level data — actual measurements collected by a NOAA tide gauge sensor at Sewells Point in Norfolk, Virginia. The station is located along the Elizabeth River near the Chesapeake Bay.
Water level is measured in feet above a baseline called MLLW (Mean Lower Low Water), which is the average of the lowest tide recorded each day over a 19-year period. Scientists and mariners use this baseline so water levels can be compared consistently over time.
You'll examine real water level data recorded by a NOAA tide gauge at Sewells Point, Virginia.
Tides are the regular rise and fall of sea level caused by the gravitational pull of the Moon and the Sun on Earth's oceans. As the Moon orbits Earth, its gravity pulls ocean water toward it, creating a bulge of water — a high tide. On the opposite side of Earth, another high tide forms. As Earth rotates, different locations pass through these bulges, causing tides to rise and fall roughly twice a day.
The graph shows verified water level data — actual measurements collected by a NOAA tide gauge sensor at Sewells Point in Norfolk, Virginia. The station is located along the Elizabeth River near the Chesapeake Bay.
Water level is measured in feet above a baseline called MLLW (Mean Lower Low Water), which is the average of the lowest tide recorded each day over a 19-year period. Scientists and mariners use this baseline so water levels can be compared consistently over time.
The horizontal axis shows the time of day in 24-hour format, from 00:00 (midnight) to 23:00 (11 PM), with labels at every 4 hours. The vertical axis shows Verified Water Level in feet, ranging from 0 to 4.0 ft above MLLW.
The line begins at approximately 2.98 ft at midnight, rises to a first peak of about 3.3 ft around 01:00–02:00, then falls to a low of about 0.76 ft near 07:00–08:00. It rises again to a second peak of about 3.32 ft near 13:00–14:00, then falls to the day's lowest point of about 0.66 ft near 20:00, before rising again to 1.74 ft by 23:00.
Key values:
00:00 — 2.98 ft | 01:00 — 3.26 ft | 02:00 — 3.21 ft | 03:00 — 2.82 ft
04:00 — 2.32 ft | 05:00 — 1.69 ft | 06:00 — 1.12 ft | 07:00 — 0.76 ft
08:00 — 0.77 ft | 09:00 — 1.11 ft | 10:00 — 1.70 ft | 11:00 — 2.36 ft
12:00 — 2.90 ft | 13:00 — 3.29 ft | 14:00 — 3.32 ft | 15:00 — 3.16 ft
16:00 — 2.72 ft | 17:00 — 2.07 ft | 18:00 — 1.36 ft | 19:00 — 0.89 ft
20:00 — 0.66 ft | 21:00 — 0.77 ft | 22:00 — 1.20 ft | 23:00 — 1.74 ft
The graph shows two high tides and two low tides — a pattern called a semidiurnal tide. You can also hover or tap any dot on the graph above to see the exact value at that time.