San Francisco Tides

Time Event Value Units
01:30 am Max Flood 2.6 kt
03:53 am High Tide 4.86 ft
04:48 am Slack
07:30 am Max Ebb -2 kt
08:19 am Low Tide 3.46 ft
10:24 am Slack
12:54 pm Max Flood 1.6 kt
01:54 pm High Tide 5.66 ft
02:54 pm Slack
06:54 pm Max Ebb -3.4 kt
09:06 pm Low Tide -0.4 ft
11:42 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?