Last Quarter moon @ 00.36

This how the phases occur, it's all down to the relative positions of the moon and the sun in relation to the Earth. The Moon is (except for Lunar eclipses) always half illuminated by the sun. Viewing from Earth we cannot always see the entire illuminated half, which is why we get the phases.

As the moon follows the ecliptic, for northern hemisphere observers Last Quarter moons are always easier to see in the Autumn, and difficult to see in the spring. The reverse is true for observers in the southern hemisphere.