Beelzebub's appearance dumbfounds the followers in Hell. They are kept silence by his mere presence, and at this point he is almost godlike in his appearance. He is flawed, they are all flawed, but they are utterly unaware of the lack of reality they all share. The look almost scares the most evil of creatures out there, showing us the degree of his stature. The use of summer alludes to how hot it is. The noontide air is how calm and still those in hell become. Beelzebub makes those in Hell and chaotic and noisy place, still and orderly. Milton once again plays with this contradictory dichotomy as Beelzebub is about to address the masses.
-Erik Scott