Weather at the Big Sur International Marathon is less about temperature than it is about wind and fog — the two variables that actually decide how hard a given year's race feels. This guide covers what race-day conditions typically look like and how to prepare, without pinning down specific numbers that can vary meaningfully from one year to the next (the climate data card on this page has verified typical figures, if that's what you're after).

The marine layer

Late April mornings on this stretch of coast are frequently blanketed in marine layer fog, and the start — deep in a redwood forest a few miles inland from the open coast — tends to run cold and damp regardless of what the rest of the day does. Most years, that fog burns off as the morning goes on, and conditions warm and brighten noticeably by the time later finishers are coming in. Some years, it lingers longer than that. Because the pattern is genuinely unpredictable more than a day or two out, it's worth checking the forecast close to race weekend rather than packing based on what a past year's race report described.

Wind is the real variable

If there's one thing to plan around at this race, it's wind. Long stretches of the course — particularly from the point where the course leaves the redwoods through the climb to Hurricane Point and beyond — run fully exposed to the Pacific, with no tree cover or buildings to break a headwind. A calm morning and a windy one produce noticeably different races on the exact same course and the exact same fitness; the wind is capable of turning a strong effort into a grind in a way temperature alone rarely does. This is a big part of why the course has a reputation for being harder than its elevation profile alone would suggest.

What to wear

The practical challenge is dressing for a start that's cold and sheltered and a course that's going to get warmer and windier as it goes. A throwaway layer for the pre-race wait and early shaded miles is close to standard advice among returning runners, since race morning starts well before sunrise and the redwood canopy holds onto the cold. Something wind-resistant and packable for the exposed coastal miles is also worth considering, particularly if the forecast is trending breezy — it's easier to carry a light layer you don't end up needing than to wish you had one on an exposed headland.

Conditions change mile to mile

Conditions also shift noticeably from one section of the course to the next, which is easy to underestimate when you're only looking at a single forecast for the day. The shaded, forested opening miles run meaningfully colder than the open coastline that follows, and the fully exposed stretch around Hurricane Point tends to feel colder still once wind is factored in, even if the air temperature there is technically no lower than a few miles back. By contrast, the Carmel Highlands near the finish regain some tree and terrain cover, which can make the closing miles feel calmer than the middle of the race even as the sun climbs higher. Dressing for one static temperature rarely works well here; dressing for a range, with something removable for the middle miles, tends to work better.

When weather has changed the race

Coastal weather here isn't just a comfort issue — it's occasionally an operational one. Highway 1 through this stretch is prone to landslides during wet winters, and the course has been altered in past years when storm damage closed sections of the road, most recently in the mid-2020s. It's a reminder that this race runs on a real, occasionally unstable coastal highway rather than a controlled urban grid, and that course details you read about in an older race report aren't guaranteed to match the current year if conditions have forced a change.