blueblack cold, weekday weather

[Tait-ka]

Sundays too my father got up early,
and put his clothes on in the
blueblack cold,
then with cracked hands that ached
from labor in the weekday weather
made banked fires blaze. No one ever thanked him.

Source: Those Winter Sundays
(Robert Hayden, 1913-1980)

Can I ask what "blueblack cold" and "weekday weather" mean in this stanza?

 

[emsr2d2]

It's cold and the sky is still black but probably starting to show very faint signs of blue as it gets towards sunrise.
His hands have become cracked due to labouring in the cold weather but he only works on weekdays.