The boiling point depends upon the intermolecular forces of attraction and hence the boiling point of Haloalkanes is higher as compared to those of corresponding alkanes due to strong dipole-dipole interaction between molecules.
As we go down in the homologous series of haloalkanes, the van der Waals forces of attraction become stronger due to an increase in molecular size and mass, hence the boiling point increases down the homologs series.
The boiling point of isomeric alkyl halides decreases with branching due to a decrease in surface area.