December is Hawaii's cooler, wetter season, but on Honolulu's calendar that's a relative description, not a mainland marathoner's one. This guide covers the general climate patterns behind race day; RaceRove's companion guide on running the Honolulu Marathon in the heat covers what to actually do about them.

Honolulu's December climate

Honolulu sits close enough to the equator that its seasons stay mild year-round, and December — while it's the island's wetter, breezier stretch of the year — doesn't bring anything like a real cold snap. Mornings start warm rather than cool, and conditions climb steadily as the sun gets higher through the morning. The exact averages for race day are on the facts card elsewhere on this page; the pattern worth planning around is steady warming from an already-mild start, not any real cold to contend with.

Why the race starts in the dark

The marathon's early start is a direct response to this climate: beginning well before sunrise gives every runner in the field at least some miles in cooler, pre-dawn conditions before the day's heat builds. It's a meaningful head start, but only a partial fix. Sunrise in Honolulu in December arrives around 7 a.m., so even runners near the front of the field spend real time racing in daylight, and slower runners spend most of their race in full sun.

Rain, wind, and what to actually expect

December falls within Hawaii's wetter season, so brief showers are a real possibility on race morning. Historical weather data for Honolulu in December shows a meaningful share of days with at least some rain, though showers here are typically short, localized trade-wind showers that clear by midday rather than an all-day soaking. Trade winds are a near-constant presence on Oahu and tend to blow moderately along the coastal stretch of the course, which can take some edge off the heat on exposed sections. Humidity is the more consistent factor: December is one of Honolulu's more humid months, not an occasional exception, and it changes how the same air temperature feels compared to a drier mainland race. Occasionally, trade winds give way to so-called 'Kona' wind patterns from the south, which tend to bring warmer, stickier, and rainier conditions — an uncommon but real possibility worth knowing about.

How it compares to other winter marathons

Runners coming from a December marathon on the mainland, or comparing this race to a spring or fall major, should recalibrate rather than assume 'winter' means 'cool.' Honolulu's December conditions have more in common with a warm-weather spring race than a typical winter one, and pacing plans built around mainland December training runs often don't survive contact with the real conditions here.

The short version

If you're building a race-morning plan, treat this as a warm, humid race that happens to fall in December, not a cold-weather one. For the practical strategies — hydration timing, pacing adjustments, what to wear — see RaceRove's dedicated guide to running the Honolulu Marathon in the heat.