Race-day weather · Sunday, May 2, 2027

OC Marathon weather.

16 OC Marathon race mornings since 2009, measured hour by hour: temperature, dew point, wind, rain, and what the weather cost runners. The forecast for the 2027 race goes live here on Apr 26, six days out.

110 Typical score
at the start The median race morning since 2009: 59°F air + 51°F dew point at 5:30am, across 16 race mornings at the John Wayne Airport (Santa Ana) weather station. Barely a penalty: 0% to 0.5% slower.
Start · 5:30am11059° air · 51° dew point
+2 hours · 7:30am11261° air · 51° dew point
+4 hours · 9:30am11463° air · 51° dew point

The OC Marathon course, mile by mile: the elevation, every climb, and how I’d run each stretch.

Your goal pace on a typical race morning

Built from the median race morning since 2009, averaged across the hours you’d be running. Where the weather costs time, each cell gives the adjusted finish time and the pace per mile to run instead. Six days out, the real forecast replaces it.

Goal on a cool dayAdjusted finish
2:456:18/mi2:46 to 2:476:19–6:21/mi0.5% to 1% slower · score 111
3:006:52/mi3:01 to 3:026:54–6:56/mi0.5% to 1% slower · score 111
3:157:26/mi3:16 to 3:177:28–7:31/mi0.5% to 1% slower · score 112
3:308:01/mi3:31 to 3:328:03–8:05/mi0.5% to 1% slower · score 112
3:458:35/mi3:46 to 3:478:37–8:40/mi0.5% to 1% slower · score 112
4:009:09/mi4:01 to 4:029:12–9:15/mi0.5% to 1% slower · score 112
4:3010:18/mi4:31 to 4:3310:21–10:24/mi0.5% to 1% slower · score 113
5:0011:27/mi5:01 to 5:0311:30–11:33/mi0.5% to 1% slower · score 113
How I’d race a typical year

Start 2 to 3 seconds per mile slower than goal through the first 10 miles. Drink early, because by the time you feel the heat the deficit is already there, and race the last 10K on feel.

Race week, start to finish: how I’d run the three-week taper, what to take in during the race, how much to slow down in heat and humidity, and what the four weeks after should look like.

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OC Marathon weather history: every race morning since 2009

Every row in the table below is a measurement from the John Wayne Airport (Santa Ana) weather station, taken nearest 5:30am (today’s first-wave start) and again three hours later. Start times have moved over the years, so treat 5:30am as a clock time, not always the gun. Across 16 race mornings:

  • A typical 5:30am reading is 59°F with a 51°F dew point, a combined score of 110.
  • The warmest was 2014: 63°F with a 53°F dew point at 5:30am, a score of 116.
  • The most humid was 2018, with a 55°F dew point.
  • The coldest was 2017, at 51°F.
  • On 14 of 16 race mornings the 5:30am score was above 100, enough to call for a pace adjustment. Three hours later, 15 of 16 were.
  • The windiest start was 2017: ESE wind at 10 mph.
  • Rain fell in the first 5 hours on 2 of 16 race mornings.
OC Marathon weather by year · air / dew point (°F), combined score, wind and rain
YearDateAir / dew at 5:30amScoreAir / dew at 8:30amScoreWind at 5:30amRain
2026May 361° / 51°11263° / 51°114CalmDry
2025May 457° / 50°10758° / 52°110S 6 mphLight rain
2024May 557° / 50°10759° / 42°101WSW 9 mphgusts 16Dry
2023May 756° / 49°10563° / 50°113CalmDry
2022May 160° / 53°11364° / 52°116ESE 5 mphDry
2021–No marathon (half marathon and 5K only, November)
2020–Cancelled (COVID-19), virtual only, no race morning
2019May 560° / 51°11162° / 50°112SW 5 mphDry
2018May 659° / 55°11464° / 54°118CalmDry
2017May 751° / 47°9854° / 49°103ESE 10 mph0.06 in
2016May 157° / 50°10762° / 53°115CalmDry
2015May 361° / 53°11463° / 51°114SSE 3 mphDry
2014May 463° / 53°11670° / 51°121CalmDry
2013May 561° / 52°11362° / 51°113S 7 mphDry
2012May 659° / 53°11261° / 52°113CalmDry
2011May 155° / 33°8875° / 14°89CalmDry
2010May 256° / 49°10562° / 47°109SE 3 mphDry
2009May 361° / 54°11462° / 54°116CalmDry

Readings from the John Wayne Airport (Santa Ana) ASOS weather station (NOAA/FAA, via the Iowa Environmental Mesonet), the observation nearest each hour. Scores above 100 call for a pace adjustment. Rain is the total the station measured in the 5 hours after 5:30am. Download every hour as a CSV.

How the score works

Add the air temperature to the dew point, both in Fahrenheit. That combined score is closer to what your body feels than the temperature alone, because dew point decides whether your sweat can evaporate, and evaporating sweat is how you shed heat at race pace. The bands below are the same ones my heat pace calculator uses, and that page has the full chart and the physiology behind it.

Combined score → how much to slow down
  • 100 or lessNo pace adjustment
  • 101 – 1100% to 0.5% slower
  • 111 – 1200.5% to 1% slower
  • 121 – 1301% to 2% slower
  • 131 – 1402% to 3% slower
  • 141 – 1503% to 4.5% slower
  • 151 – 1604.5% to 6% slower
  • 161 – 1706% to 8% slower
  • 171 – 1808% to 10% slower
  • Above 180Hard running is not recommended

The bands are a coach's rule of thumb, not a lab measurement. Treat each range as a starting point and let effort make the final call.

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Other race-day weather pages

Twin Cities MarathonSunday, October 4, 202695Race day at the startNo adjustment needed Chicago MarathonSunday, October 11, 2026113Race day at the startSlight penalty: 0.5% to 1% slower Columbus MarathonSunday, October 18, 202664Forecast at the startNo adjustment needed Detroit MarathonSunday, October 18, 202672Forecast at the startNo adjustment needed Marine Corps MarathonSunday, October 25, 202694Typical startNo adjustment needed NYC MarathonSunday, November 1, 202683Typical startNo adjustment needed Philadelphia MarathonSunday, November 22, 202673Typical startNo adjustment needed California International MarathonSunday, December 6, 202683Typical startNo adjustment needed Honolulu MarathonSunday, December 13, 2026136Typical startReal penalty: 2% to 3% slower Houston MarathonSunday, January 17, 202784Typical startNo adjustment needed LA MarathonSunday, March 7, 202799Typical startNo adjustment needed Atlanta MarathonSunday, March 7, 202797Typical startNo adjustment needed Jersey City MarathonSunday, April 18, 202791Typical startNo adjustment needed Boston MarathonMonday, April 19, 202784Typical startNo adjustment needed Rock 'n' Roll Nashville MarathonSaturday, April 24, 2027111Typical startSlight penalty: 0.5% to 1% slower Eugene MarathonSunday, April 25, 202789Typical startNo adjustment needed Big Sur MarathonSunday, April 25, 202796Typical startNo adjustment needed Flying Pig MarathonSunday, May 2, 2027102Typical startBarely a penalty: 0% to 0.5% slower Pittsburgh MarathonSunday, May 2, 202799Typical startNo adjustment needed Colfax MarathonSunday, May 16, 202781Typical startNo adjustment needed Rock 'n' Roll San Diego MarathonSunday, June 6, 2027119Typical startSlight penalty: 0.5% to 1% slower Grandma's MarathonSaturday, June 19, 2027112Typical startSlight penalty: 0.5% to 1% slower San Francisco MarathonSunday, July 25, 2027109Typical startBarely a penalty: 0% to 0.5% slower

Course guides, mile by mile: Twin Cities Marathon, Chicago Marathon, Columbus Marathon, Detroit Marathon, Marine Corps Marathon, NYC Marathon, Philadelphia Marathon, California International Marathon, Honolulu Marathon, Houston Marathon, LA Marathon, Jersey City Marathon, Boston Marathon, Rock 'n' Roll Nashville Marathon, Eugene Marathon, Big Sur Marathon, Flying Pig Marathon, Pittsburgh Marathon, Colfax Marathon, Rock 'n' Roll San Diego Marathon, Grandma's Marathon, San Francisco Marathon. All race-day weather pages.

RunFitCoach is not affiliated with the Hoag OC Marathon or its organizers. Observations from the John Wayne Airport (Santa Ana) ASOS station (NOAA/FAA) via the Iowa Environmental Mesonet. Data updated Saturday, October 17, 2026.

Heat is one variable. I plan for all of them.

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