The size and timing of tides change as the Moon, Sun, and Earth continually shift position. Their changing angles—called declination relative to Earth’s equator—can make successive high or low tides unequal and can affect the strength of tidal currents.
Near a new or full Moon, the Sun, Moon, and Earth are broadly aligned. Their tide-generating forces reinforce one another and usually create a larger tidal range called a spring tide. The name has nothing to do with the season. Near the first- and third-quarter Moon, the Sun and Moon act at roughly right angles, partially offsetting one another and usually producing a smaller range called a neap tide. Most lunar months contain two spring-tide periods and two neap-tide periods.
Distance also matters. The Moon’s elliptical orbit brings it closer to Earth at perigee and farther away at apogee, strengthening or weakening its tidal influence. Earth’s changing distance from the Sun has a smaller annual effect. These cycles shape the astronomical tide, but local geography and weather can reinforce or offset them, so a new or full Moon does not guarantee a location’s highest observed water.
Source: NOAA Tides and Water Levels