Why do many covalent hydrides have low melting points and boiling points?

Most covalent hydrides are volatile compounds that exhibit low melting and boiling points because they are held together in the condensed state primarily by relatively weak van der Waals intermolecular interactions.1

Because these intermolecular forces are weak, they require relatively little thermal energy to overcome, allowing the substances to transition into liquid or gaseous states at lower temperatures. This is in contrast to compounds where stronger forces, such as hydrogen bonding, are present; in those specific cases, the boiling points are significantly higher because additional thermal energy is required to break those stronger bonds.12