San Francisco Tides

Time Event Value Units
12:34 am Max Flood 1.4 kt
01:28 am High Tide 5.54 ft
02:25 am Slack
06:19 am Max Ebb -3.5 kt
08:36 am Low Tide -0.67 ft
11:22 am Slack
02:20 pm Max Flood 2.1 kt
04:27 pm High Tide 4.17 ft
05:41 pm Slack
08:10 pm Max Ebb -1.5 kt
08:14 pm Low Tide 3.42 ft
10:53 pm Slack
What day is the longest?
Why are there 2 tides per day?
Why doesn't Slack = High/Low Tide?
Why can you ride a flood but not an ebb?