Is it hot at Diamond Head?

Climbing Diamond Head: a sun-baked crater trail and when to go

The trail up Diamond Head runs through the inside and up the rim of an old volcanic crater above Honolulu, and it is almost entirely in the open. There are no big trees on the ascent, little shade on the switchbacks, and a warm tropical sun overhead for most of the year. The hike is not long, but the exposure is constant, so the smart move is going early.

Warm year-round, exposed all the way up

Honolulu barely changes season to season. Afternoon highs hover around 83°F in high summer and stay in that same band, upper 70s to mid-80s, every month. It is pleasant, consistent warmth rather than dangerous heat, so the concern on Diamond Head is sun and the effort of the climb more than extreme temperature. What makes it feel hot is the lack of cover: the crater floor and the trail up the interior wall soak up sun, and the reflected heat off the rock and paved sections adds to it.

The tropical sun here is strong. By 3 PM in July it sits about 57 degrees up and, unusually, comes almost straight from the west. Because Honolulu is so far south, the summer sun tracks high and the shadows stay short through the middle of the day, which is exactly when the trail offers the least relief.

Where the little shade there is falls

Be honest with yourself: this is an exposed hike. The shade that exists is patchy and comes from the crater walls rather than any tree canopy.

• The interior crater walls throw shade onto parts of the trail in early morning and late afternoon, depending on which way the path faces.
• The tunnel and stairway sections near the top give brief relief from direct sun.
• The open switchbacks and the summit lookout are full sun, with a clear sky overhead.

To see how the crater rim shades the trail below it as the sun moves, the satellite shadow view shows the bowl from above.

Go early, carry water

The single best decision is starting the hike soon after the gate opens. In July the sun is up around 5:58 AM and sets near 7:16 PM, and the early hours are cooler, less crowded, and the crater wall still shades a good part of the lower trail. By mid-morning the sun is high and the switchbacks are fully exposed, and by midday the summit is a hot, bright place to stand.

Bring more water than you think you need, wear a hat and sunglasses, and put on sunscreen before you start, because there is nowhere on the way up to wait out the sun. Since Honolulu's warmth is steady all year, there is no cooler season to wait for, which makes the time of day the only real lever you have. Climb Diamond Head at first light, use the crater wall's morning shade while it lasts, and you will be back down before the trail turns into a sun trap.