org-agenda-deadline-faces

org-agenda-deadline-faces is a variable defined in `org-faces.el'.
Its value is

((1.0 . org-warning)
 (0.5 . org-upcoming-deadline)
 (0.0 . default))

Documentation:
Faces for showing deadlines in the agenda.
This is a list of cons cells. The cdr of each cell is a face to be used,
and it can also just be like '(:foreground "yellow").
Each car is a fraction of the head-warning time that must have passed for
this the face in the cdr to be used for display. The numbers must be
given in descending order. The head-warning time is normally taken
from `org-deadline-warning-days', but can also be specified in the deadline
timestamp itself, like this:

DEADLINE: <2007-08-13 Mon -8d>

You may use d for days, w for weeks, m for months and y for years. Months
and years will only be treated in an approximate fashion (30.4 days for a
month and 365.24 days for a year).

You can customize this variable.