Because the air has had all night to cool down from the lack of solar energy.
just before dawn
Flags are supposed to be lowered at night. You generally raise the flag at colours (0800) and lower them at sunset. If 0800 is before dawn, you raise the flag at 0800, lower it immediately, then raise the flag again at dawn.
BTD - Before the Dawn - was created in 2010.
Before the Dawn - novel - was created in 1935.
The ISBN of Darkness Before Dawn is 0689830807.
Before the Dawn - band - was created in 1999.
The duration of The Hour Before the Dawn is 1.25 hours.
Darkness Before Dawn has 272 pages.
The duration of Decision Before Dawn is 1.98 hours.
Darkest before the dawn is not a biblical saying
Operation Before the Dawn happened on 1983-02-06.
The Hour Before the Dawn was created on 1944-05-10.