What is the weather like in Hilo end of May, early June?

Hilo is "dry" from May to about July. When I moved here it was in May and the town was in the middle of a drought. It hadn't rained once in 3 weeks. The lawn at the house I stayed in while building my home was brown and crispy. I haven't seen it go that long without rain here in years now, but it's still pretty dry late spring to early summer.

Bring clothes for warm weather - you won't need jeans and a sweater unless you plan to come up to the summit of Mauna Kea (it's a blizzard up here right now, snowed in) but be aware the weather changes quickly. Hilo is the rainiest city in the United States (130"+/year) and when it rains it pours. The rain can make it very cool, especially at night.

BTW, if you've never been to Hilo, I hate to burst your tropical vacation ideas - but there are no white sand beaches anywhere on this side of the island - and the black sand beaches aren't that nice. Kona is the dry, warm, white sand beach side. Heads up

May and June are the "driest" month in Hilo, but Hilo still averages about 8 inches of rain for each of those months. The daily low will be around 70 and the high will be around 80.

Hilo is very rainy most of the year