Pack or skip
Beanie for Hilo in September
Verdict
Skip it
Lows near 65°F — no scenario where you'll want one.
Why
Hilo in September averages highs of 82°F, lows of 65°F, 15 rainy days.
That climate means a beanie isn't pulling its weight. Lows near 65°F — no scenario where you'll want one.