Here's why:

* Gravitational Pull: The moon's gravitational pull is strongest during these phases. This pull, combined with the sun's gravitational pull, creates a stronger tidal force.

* Alignment: During new and full moon phases, the sun, earth, and moon are aligned, resulting in a stronger combined gravitational pull on the earth's oceans. This pull leads to higher high tides and lower low tides.

Note: Tides are influenced by many factors, including the position of the sun and moon, the shape of the coastline, and ocean currents. Therefore, the exact timing of low tides can vary depending on location.