High tides
link (and of course, low tides) come at different times every day because the Moon moves in its orbit. Every day the Moon moves about
link 13º further along its orbit, so every day, any given high or low tide (there are two per day, thanks to the symmetry of the tidal bulge) is going to arrive slightly later than the previous day. According to New York City's tide chart, the morning high tide on January 28th is due in at 4:16AM, but on the 29th
link it will occur at 5:23AM.