This is a day of the week. You know this because it has 曜日 in it. But what day of the week is it? The fire day of the week is the day after the worst day of the week (Monday). You set fire to everything because you're so pissed off about yesterday, which makes today Tuesday.

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. Just watch out for the ひ becoming a び like it did in the word 曜日.