December, Australia

[hylas]

The grey sky hung like a flannelette sheet.
Frayed a bit with yellow light, the centre traps
the muggy air. The sea will wet the hems of it.

I think my Nan has tucked it there.
Anxious in December that we might catch chill,
she snuck in with the moon as we slept.

[matsunosuperfan]

The grey sky hangs like a flannelette sheet,
I think my Nan has tucked it there.

Frayed with yellow light, the centre traps
the muggy air. 

The sea will wet the hems, anxious
that we might catch chill

in December, as we slept
she snuck in with the moon.

--
I mean I like it as is but I think you could maybe play with the sequencing of images in potentially even more eprovicative ways

[Tiger the Lion]

The grey sky hangs like a flannelette sheet,
I think my Nan has tucked it there.

Frayed with yellow light, the centre traps
the muggy air. 

The sea will wet the hems, anxious
that we might catch chill

in December, as we slept
she snuck in with the moon.

I fail to see how a rewrite without any corresponding explanation is helpful to the OP. Not appropriate for a workshop forum.
- Admin

[busker]

The grey sky hung like a flannelette sheet.
Frayed a bit with yellow light, the centre traps
the muggy air. The sea will wet the hems of it. … nice. I’m undecided on the “a bit”, does the line sound better without? Otherwise, original and interesting 

I think my Nan has tucked it there.
Anxious in December that we might catch chill,
she snuck in with the moon as we slept. ….. the “as we slept” makes the line too long. If you could somehow move the “as we slept” to the lines above, ending on “moon” would be perfect. After writing this comment, I saw that Matsun has provided an example. I don’t like her particular example as I think you need to end the previous train of thought on “hems of it” as you’ve done,  and still keep it to two strophes rather than several couplets, but you get the general idea

Nice one. Thanks for posting