Best Marathons for Perfect Racing Weather in 2026

Which marathons have the best racing weather? We rank races by temperature, humidity, and wind data to help you avoid DNFs and run your fastest.

Heat is the one race-day variable training cannot fix. Research on the Boston, New York and Twin Cities fields (Ely et al., 2007) shows marathon times slow progressively as wet-bulb globe temperature climbs from 5 to 25 degrees Celsius, and the effect hits mid-pack and slower runners hardest. So the smartest way to protect a goal time is to pick a race that is statistically cool to begin with. The 19 marathons below are ranked by average race-day temperature, from the single-digit chill of Osaka and Seoul (about 6C) up through the autumn sweet spot of Chicago, Valencia and Amsterdam (10-12C) to mild outliers like Lisbon (18C) and subtropical Naha (21C). Use our Weather Score to rate any race day, then the Pace Calculator to lock in cool-weather splits.

Temperature is only half the story: humidity and dew point decide how much of that cool air actually helps you. Dew point below about 55F (13C) means weather has essentially no drag on your pace, while above 60F slows everyone. That is why a foggy 13C July race like San Francisco can beat a clear, humid October day elsewhere. The list spans nine months and twelve countries precisely because cool, dry conditions show up at different times around the world, so you can target a fast climate whatever season you train through. Check the dew-point math before you enter with our Finish Time Calculator.

How We Selected These Marathons

  • Average race-day temperature in the cool band, from 6C (Osaka, Seoul) up to a mild 14C ceiling for the core picks
  • Race held in a cool-season month: autumn (Sep-Oct), winter (Dec-Feb) or spring (Mar-May), never peak summer except fog-cooled San Francisco
  • Documented average temperature for the race location in our marathon database, shown in the ranked table below
  • Typically low humidity with a race-morning dew point near or below 55F (13C), the threshold below which weather stops dragging on your pace
  • Established large-field events with consistent year-to-year climate data (Berlin ~48,000, Chicago ~54,000, Beijing ~32,000)
  • Warm-climate outliers (Lisbon 18C, Naha 21C) clearly flagged so you choose them by scenery, not by mistake

Our Top Picks

# Race DateAvg TempHumidityRain ChanceElevation
1 Ibusuki Nanohana Marathon January 10, 20279°C65%30%100 m
2 Amsterdam Marathon October 18, 202610°C80%35%10 m
3 Beijing Marathon October 25, 202610°C50%10%55 m
4 Chicago Marathon October 11, 202612°C65%25%35 m
5 Osaka Marathon February 28, 20276°C66%29%21 m
6 Seoul Marathon March 15, 20266°C50%20%93 m
7 Valencia Marathon December 6, 202612°C65%15%15 m
8 Mesa Marathon February 13, 202712°C30%5%50 m
9 Barcelona Marathon March 14, 202712°C65%10%134 m
10 Vancouver Marathon May 2, 202712°C75%35%250 m
Show all 19 races
# Race DateAvg TempHumidityRain ChanceElevation
11 Copenhagen Marathon May 10, 202613°C60%15%15 m
12 San Francisco Marathon July 26, 202613°C80%5%397 m
13 Berlin Marathon September 27, 202614°C65%25%20 m
14 Nike Melbourne Marathon October 11, 202614°C60%20%185 m
15 Prague Marathon May 3, 202614°C55%15%50 m
16 Fukuoka Marathon November 8, 202614°C60%20%35 m
17 REVEL Mt Charleston Marathon April 3, 202714°C31%5%52 m
18 Lisbon Marathon October 10, 202618°C65%10%85 m
19 Naha Marathon December 6, 202621°C68%25%180 m

Built from official course data for 349 races · as of July 6, 2026

Frequently Asked Questions

What is the ideal temperature for running a marathon?

Research consistently points to roughly 7-12C (45-54F) for the fastest times. The Ely et al. (2007) analysis of seven North American marathons found performance degrades steadily as wet-bulb globe temperature rises from 5C to 25C, with slower runners losing the most. On this list, Osaka and Seoul sit at about 6C, while Chicago (12C), Valencia (12C) and Amsterdam (10C) land squarely in the fast zone. Run any race day through our Weather Score to see how its conditions compare.

Is humidity or temperature more important for marathon performance?

Dew point is the single best predictor because it folds temperature and humidity into one number. Below about 55F (13C) dew point, weather barely touches your pace; above 60F, everyone slows, and a 4-hour runner can lose 15-25 minutes on a high-dew-point day. That is why a cool, dry Valencia in December outruns a warm, sticky race at the same air temperature, and why dry-air Beijing in late October is a reliable PB climate. Model your own conditions with our Pace Calculator.

Which marathon on this list has the coolest weather?

Osaka (late February, ~6C) and Seoul (mid-March, ~6C) are the coldest in the field, cold enough that throwaway layers and gloves at the start are standard, with Osaka occasionally seeing snow in its final miles. Close behind is Japan's Ibusuki Nanohana (~9C) and autumn's Amsterdam and Beijing (~10C). These deliver the crisp air fast runners want, but they demand a warm-up plan and proper start-line clothing you can discard.

Can a summer marathon ever have good racing weather?

Almost never, with one famous exception on this list: the San Francisco Marathon. Held in late July, it stays around 13C because the city's signature marine fog rolls in during summer mornings, keeping start temperatures in the low-to-mid 50s F with virtually no rain. It is widely called the coolest summer marathon in the United States. Outside of fog-cooled microclimates like this, summer races almost always mean heat and humidity that wreck pacing.

Which races on this list are warmest, and should I still consider them?

Naha in Okinawa (December, ~21C) and Lisbon (October, ~18C) are the warmest picks, both well above the ideal fast-running band. Naha is subtropical Okinawa's biggest citizen marathon and a genuinely fun travel race, but it is a finish-it-and-enjoy-it event, not a PB target. Melbourne and Berlin (~14C) sit at the top of the comfortable range. If a fast time is the goal, lean toward the sub-12C picks; if scenery and experience matter more, the warmer races are still excellent.

How much can good weather actually improve my marathon time?

The swing is large. Studies show 3-10% performance loss in hot conditions, meaning a 3:30 marathoner might run 3:40 to 3:51 in 25C heat versus their cool-weather potential. Choosing a race like Berlin, Chicago or Valencia in its cool window removes that penalty before you even start training. Set a realistic, climate-adjusted goal with our Finish Time Calculator, and cross-check it against the best marathons for a PR.

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