Strange
Curious, Odd
な adjective
That's very odd and strange, making it odd and strange.
きみょう
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
今年の夏が例年になく暑かったせいなのかは分かりませんが、奇妙な発疹が胸に出ましてね。
I’m not sure if it was because this summer was unusually hot, but a strange rash broke out on my chest.