warm
昫 centers on warmth, specifically the gentle warmth of the sun.
昫 combines 日 (sun) with 句, which likely contributes the sound. The exact historical development of 句 in this character is uncertain.
The sun 日 on the left and the curved shape 句 on the right suggest the sun's rays bending around to spread warmth.
For ク, imagine a cool morning where the sun's warmth is just starting to feel cozy: coo -> ク, and the sun 日 brings that gentle warmth.