Collocations for sky - noun

big, vast, wide
open
We slept under the open sky.

empty
bright, clear, cloudless, sunny
a week of cloudless skies

hazy, smoggy
cloudy, dull, overcast
stormy
star-filled, starlit, starry, star-studded
moonlit
dark, darkening, pale
azure, blue, cerulean (esp. AmE)
I opened my shutters and saw a brilliant blue sky.

grey/gray, leaden
black, inky, moonless
the pale moon in the inky night sky

morning, night, etc.
January, spring, winter, wintry, etc.
northern, southern, etc.
desert
the vast desert skies

patch
a patch of blue sky

illuminate, light up
The fireworks lit up the sky.

fill
Flocks of flamingoes fill the sky.

scan, watch
Astronomers scan the night skies for asteroids.

patrol

clear, clear up, lighten
The rain stopped and the skies cleared.

cloud over (esp. BrE), darken, turn grey/gray
The afternoon sky turned orange.

be streaked with sth
The sky was streaked with gold.

glow (with sth), light up (with sth)
The sky glows red with fire.

open (= start raining)
The skies opened and rain poured down.

across the sky
Black clouds spread across the sky.

against the sky
The eagle was black against the morning sky.

beneath a … sky, under a … sky
a ship tossing under a dark sky

from the sky, out of the sky
A strange object dropped out of the sky.

in the sky
There was a kite high up in the sky.

sky above
A helicopter appeared in the sky above them.

sky over
to patrol the skies over the Atlantic

high in the sky, low in the sky
when the sun is low in the sky

the sky above, the sky overhead
Swallows darted about in the sky overhead.

the sky is falling (figurative, esp. AmE)
alarmists who claim that the sky is falling

reach for the sky (often figurative)
My philosophy has always been to reach for the sky.

take to the skies (= to go into the sky)
Some vintage aircraft will be taking to the skies at this weekend's fair.