https://runfast.tech/blog/Heat, humidity and weather for runners.en https://runfast.tech/blog/live-tracking-for-running-events/https://runfast.tech/blog/live-tracking-for-running-events/Fri, 16 Oct 2026 08:00:00 GMTLive tracking for running events puts every runner on one map while the race is on. Each runner's phone sends their position, and supporters see their dot, distance, pace and finish time, in any browser. On livedot, the course is also coloured by how hard the heat makes each stretch, and organisers get the race set up free. https://runfast.tech/blog/garmin-race-day-weather/https://runfast.tech/blog/garmin-race-day-weather/Tue, 13 Oct 2026 08:00:00 GMTGarmin race day weather lives on the primary race glance. Add a race in Garmin Connect and your watch shows a countdown, your goal or predicted time and the weather: history at once, a forecast about 14 days out. Garmin's manuals list no dew point or heat stress along the course; RunFast's Map your run shows both per kilometre. https://runfast.tech/blog/epic-ride-weather-for-running/https://runfast.tech/blog/epic-ride-weather-for-running/Mon, 12 Oct 2026 08:00:00 GMTEpic Ride Weather works for running in part. It forecasts any route at your start time and pace, with temperature, feels like, wind, rain and air quality. But it's built for cyclists: its pages describe riding speed, not min:sec pace, and mention no dew point or heat stress. RunFast's Map your run, TrueEffort and GPX Forecast are runner-friendly alternatives. https://runfast.tech/blog/runna-adapt-for-heat/https://runfast.tech/blog/runna-adapt-for-heat/Sun, 11 Oct 2026 08:00:00 GMTRunna's Adapt for Heat slows your session's pace targets when the forecast feels like temperature tops about 20 °C (68 °F), sooner on long runs. It works the day before or on the day, for the hour you pick, and suits Runna subscribers. Free alternatives: Running Writings for a number, RunFast's Map your run for heat along a route. https://runfast.tech/blog/wyndo-alternatives/https://runfast.tech/blog/wyndo-alternatives/Sat, 10 Oct 2026 08:00:00 GMTThe best Wyndo alternative depends on what you're missing. RunWeather puts a run score and best window in a phone app, Racecast and MeteoPace cover more races, including London, and Route Forecast times the weather along a route file. RunFast's free Map your run adds heat stress for every kilometre of your own route at your pace. https://runfast.tech/blog/meteopace-alternatives/https://runfast.tech/blog/meteopace-alternatives/Fri, 09 Oct 2026 08:00:00 GMTThe best MeteoPace alternatives cover its paid splits for free. Racecast gives free forecasts and a weather-adjusted pace calculator, Wyndo a free heat calculator and race history, TrueEffort free hill-adjusted splits from your file, and GPX Forecast free weather along a GPX. RunFast's Map your run times heat stress to every kilometre, free. https://runfast.tech/blog/racecast-alternatives/https://runfast.tech/blog/racecast-alternatives/Thu, 08 Oct 2026 08:00:00 GMTThe best Racecast alternatives depend on what you need. MeteoPace builds a deeper split-by-split race plan, Wyndo shows free start-line history and a cited heat calculator, FindMyMarathon times named races to your goal, and TrueEffort reads your own route file. RunFast's free Map your run adds heat stress for every kilometre at your pace. https://runfast.tech/blog/what-to-wear-marathon/https://runfast.tech/blog/what-to-wear-marathon/Wed, 07 Oct 2026 08:00:00 GMTWhat to wear for a marathon depends on the weather between your start and your finish, not the forecast for the start. Wear kit you've tested on long runs, chosen for mid-race. Add a throwaway layer for a cold start, a light shell and gloves for cold rain, and a cap, sunscreen and pale singlet for heat. https://runfast.tech/blog/what-to-wear-running-temperature/https://runfast.tech/blog/what-to-wear-running-temperature/Tue, 06 Oct 2026 08:00:00 GMTWhat to wear running depends on the feels like at your pace, not the air temperature alone. Dress as if it's about 5–8 °C (10–15 °F) warmer than it is: shorts and a T-shirt from about 10 °C (50 °F), long sleeves below that, and gloves, tights and a windproof jacket near freezing. https://runfast.tech/blog/free-running-weather-tools/https://runfast.tech/blog/free-running-weather-tools/Mon, 05 Oct 2026 08:00:00 GMTThe best free running weather app is often not an app at all. Dress My Run suggests what to wear, Apple Weather shows dew point on any iPhone, and Route Forecast and GPX Forecast time the weather along a route file. RunFast's Map your run adds feels like and heat stress at your pace, kilometre by kilometre, with no login. https://runfast.tech/blog/best-running-weather-apps/https://runfast.tech/blog/best-running-weather-apps/Sun, 04 Oct 2026 08:00:00 GMTThe best running weather app depends on the job. To plan a named marathon, MeteoPace and Racecast go furthest. To pick the hour, RunWeather and WeatherToRun score every hour. To dress for the weather, Dress My Run is free. To see heat stress along your own route at your pace, RunFast's Map your run is a free browser tool. https://runfast.tech/blog/comrades-marathon-weather/https://runfast.tech/blog/comrades-marathon-weather/Sat, 03 Oct 2026 08:00:00 GMTComrades Marathon weather runs from cold to warm in one day. From 2015 to 2024, down-run starts in Pietermaritzburg averaged 7.4 °C (45 °F) at 05:30, and up-run starts in Durban 15.1 °C (59 °F). By afternoon the air reached about 21 to 27 °C (70 to 81 °F), with High heat stress in three of eight races. https://runfast.tech/blog/berlin-marathon-weather-history/https://runfast.tech/blog/berlin-marathon-weather-history/Fri, 02 Oct 2026 08:00:00 GMTBerlin Marathon weather history from 2015 to 2024 shows mild late-September mornings. The air at the 09:15 start averaged 12.7 °C (55 °F), and six of nine race days stayed at Low heat stress for a four-hour runner. The warm exception was 2021, when the air reached 23.4 °C (74 °F). https://runfast.tech/blog/london-marathon-weather-history/https://runfast.tech/blog/london-marathon-weather-history/Thu, 01 Oct 2026 08:00:00 GMTLondon Marathon weather history from 2015 to 2024 is mostly cool. The air at the start ranged from 5.8 °C (42 °F) in 2016 to 18.9 °C (66 °F) in 2018, the hottest London Marathon on record. Eight of nine race days rated Good for a four-hour runner, with Low heat stress. https://runfast.tech/blog/boston-marathon-weather-history/https://runfast.tech/blog/boston-marathon-weather-history/Wed, 30 Sep 2026 08:00:00 GMTBoston Marathon weather history from 2015 to 2024 swings widely. The air at the 10:00 start ranged from 3.2 °C (38 °F) in the cold rain of 2018 to 21.1 °C (70 °F) in 2017. Of nine race days, three rated Good, four Fair for warmth and two Tough for cold rain. https://runfast.tech/blog/marathon-weather-history/https://runfast.tech/blog/marathon-weather-history/Tue, 29 Sep 2026 08:00:00 GMTMarathon weather history for 2015 to 2024 shows the Comrades Marathon in South Africa as the hottest of four big races, reaching High heat stress on three of its eight race days. Boston swings most, from cold rain to warm sun. London is usually cool, and Berlin's late-September mornings stay mild. https://runfast.tech/blog/wind-and-hills-running-pace/https://runfast.tech/blog/wind-and-hills-running-pace/Mon, 28 Sep 2026 08:00:00 GMTRunning into the wind slows your pace more than a tailwind speeds it up. At the same effort, a 20 km/h (12 mph) headwind turns 5:00 per km (8:03 per mile) into about 5:24 (8:42), while the same tailwind gives only 4:52 (7:51). That headwind costs about as much as a 2% climb. https://runfast.tech/blog/ideal-marathon-temperature/https://runfast.tech/blog/ideal-marathon-temperature/Sun, 27 Sep 2026 08:00:00 GMTThe ideal marathon temperature for most runners is about 4–10 °C (39–50 °F) of air temperature, according to a study of 1.8 million finishes at six big-city marathons. Elite racing peaks a little warmer, at a WBGT of 7.5–15 °C (46–59 °F). Above the ideal, every degree slows you, and slower runners lose most. https://runfast.tech/blog/how-hot-is-too-hot-to-run/https://runfast.tech/blog/how-hot-is-too-hot-to-run/Sat, 26 Sep 2026 08:00:00 GMTHow hot is too hot to run depends on humidity and sun, not air temperature alone. The safer gauge is WBGT: the American College of Sports Medicine advises postponing or cancelling races above 28 °C (82 °F), with risk for everyone from 23 °C (73 °F). In humid midday sun, that High level arrives at about 20 °C (69 °F). https://runfast.tech/blog/marathon-heat-flags/https://runfast.tech/blog/marathon-heat-flags/Fri, 25 Sep 2026 08:00:00 GMTA black flag at a marathon means extreme heat stress: under the Chicago Marathon's Event Alert System, the event is cancelled or participation stopped. Green means low risk, yellow moderate, red high. The colours follow WBGT bands the American College of Sports Medicine set in 1996, with black above 28 °C (82 °F). https://runfast.tech/blog/wbgt-running/https://runfast.tech/blog/wbgt-running/Thu, 24 Sep 2026 08:00:00 GMTWBGT (wet bulb globe temperature) is the heat-stress number for running that race medical teams use. It blends air temperature, humidity, sunshine and wind into one reading. Big-city marathons grade it in four levels: Low below 18.3 °C (65 °F), Moderate to 22.8 °C (73 °F), High to 27.8 °C (82 °F), and Extreme above. https://runfast.tech/blog/heat-adjusted-pace-calculator/https://runfast.tech/blog/heat-adjusted-pace-calculator/Wed, 23 Sep 2026 08:00:00 GMTA heat adjusted pace calculator turns your cool-weather pace into the slower pace that costs the same effort in the heat. At 25°C (77°F) with a 15°C (59°F) dew point, a 5:00 per km (8:03 per mile) runner slows to 5:06–5:09 per km by Hadley's chart, or 5:07 by John Davis's model. https://runfast.tech/blog/humidity-running-pace/https://runfast.tech/blog/humidity-running-pace/Tue, 22 Sep 2026 08:00:00 GMTYes, humidity affects running pace, but mainly on warm days, and the humidity percentage is the wrong number to watch. Read the dew point. At 25°C (77°F), raising it from 10°C to 20°C (50°F to 68°F) takes the expected marathon slowdown from 1.8% to 3.3%, by John Davis's model. In cool air, humidity barely matters. https://runfast.tech/blog/good-dew-point-for-running/https://runfast.tech/blog/good-dew-point-for-running/Mon, 21 Sep 2026 08:00:00 GMTA good dew point for running is below 10°C (50°F), where humidity barely touches your pace. Up to about 13°C (55°F) still feels comfortable. From 15°C (59°F) the air turns sticky, from 18°C (64°F) hard efforts suffer, and from 21°C (70°F) it is oppressive. The warmer the day, the more each degree of dew point costs. https://runfast.tech/blog/dew-point-running/https://runfast.tech/blog/dew-point-running/Sun, 20 Sep 2026 08:00:00 GMTA dew point running chart grades how sticky the air is. Below 10°C (50°F) is comfortable; 10–15°C (50–59°F) is noticeable; 15–18°C (59–64°F) is sticky; 18–21°C (64–70°F) is hard on any fast run; 21°C (70°F) and above is oppressive. Dew point beats relative humidity because it measures the moisture itself. https://runfast.tech/blog/running-in-heat-and-humidity/https://runfast.tech/blog/running-in-heat-and-humidity/Sat, 19 Sep 2026 08:00:00 GMTRunning in heat and humidity slows you by roughly 1% at 20°C (68°F) with a 12°C (54°F) dew point, and by 3–5% at 25–30°C (77–86°F) with a dew point near 20°C (68°F). For a four-hour marathon that is 3 to 11 minutes. Slower runners lose more, and the sun and the dew point matter as much as the thermometer. https://runfast.tech/blog/feels-like-temperature-running/https://runfast.tech/blog/feels-like-temperature-running/Fri, 18 Sep 2026 08:00:00 GMTThe feels like temperature on most weather apps is worked out for someone standing in the shade, so on a sunny run it reads low. Running at 5:30 per km (8:51 per mile) in full sun at 27°C (81°F), the feels like can reach 34°C (93°F). In cold wind, your own speed makes it feel colder. https://runfast.tech/blog/best-time-to-run-in-hot-weather/https://runfast.tech/blog/best-time-to-run-in-hot-weather/Thu, 17 Sep 2026 08:00:00 GMTThe best time to run in hot weather is usually the last hour before sunrise, when the air is coolest and the sun isn't up. Heat stress climbs fast after that: in Seville on 10 July 2023 it went from Low at 07:00 to High by 09:00. When a cool change arrives, the evening can be better. https://runfast.tech/blog/marathon-forecast-accuracy/https://runfast.tech/blog/marathon-forecast-accuracy/Wed, 16 Sep 2026 08:00:00 GMTA marathon weather 10 day forecast is a rough guide to whether race week will be warm or cool, not an hour-by-hour plan. NOAA says a ten-day forecast is right only about half the time, against about 80% at seven days and 90% at five. Plan from race-day history first, then firm up inside five days. https://runfast.tech/blog/weather-along-running-route/https://runfast.tech/blog/weather-along-running-route/Tue, 15 Sep 2026 08:00:00 GMTTo get the weather along your running route, load the route as a GPX, FIT or TCX file into a tool that times the forecast to your pace. It works out when you'll reach each kilometre and reads the weather there. On one Seville half marathon morning, heat stress went from Low at the start to High by the finish. https://runfast.tech/blog/race-day-weather-forecast/https://runfast.tech/blog/race-day-weather-forecast/Mon, 14 Sep 2026 08:00:00 GMTRead a marathon race day weather forecast for your finish time, not the start. Find the hours of your halfway and last 10 km (6.2 miles), then check heat stress (WBGT), dew point and feels like. At Berlin in 2021, a 3:00 runner met Moderate heat stress from km 12; a 5:00 runner met High at km 40. https://runfast.tech/blog/running-weather-forecast/https://runfast.tech/blog/running-weather-forecast/Sun, 13 Sep 2026 08:00:00 GMTA useful running weather forecast is timed to your run, not to your town. Check the air temperature, dew point and heat stress (WBGT) for each stretch of your route at the hour you'll reach it. On Berlin's 2016 race day, a five-hour marathoner started at 12.8°C (55°F) and met 21.9°C (71°F) before the finish. https://runfast.tech/blog/fastpacking-weather/https://runfast.tech/blog/fastpacking-weather/Sat, 12 Sep 2026 08:00:00 GMTFastpacking weather planning means checking each day of a multi-day run as its own forecast: heat while you move, cold at camp, rain on kit you can't dry, wind on exposed ground and rivers after rain. Forecasts are dependable about five days out, so firm up each day as it comes into range. https://runfast.tech/blog/mountain-ultra-weather/https://runfast.tech/blog/mountain-ultra-weather/Fri, 11 Sep 2026 08:00:00 GMTMountain ultra weather changes with height and with the clock. In the standard atmosphere, air cools about 6.5 °C for every 1,000 m you climb (3.6 °F per 1,000 ft), the highest passes may come at night, and storms build on afternoons. UTMB warns of anything from above 30 °C (86 °F) to −10 °C (14 °F). https://runfast.tech/blog/ultramarathon-in-the-heat/https://runfast.tech/blog/ultramarathon-in-the-heat/Thu, 10 Sep 2026 08:00:00 GMTRunning an ultramarathon in the heat means carrying heat stress for 15 to 45 hours, not one hot hour. Western States says its course can pass 43 °C (110 °F); Death Valley's July highs average 47 °C (116 °F). Slow down early, cool with ice and water, drink to thirst, and know when your pace reaches the afternoon. https://runfast.tech/blog/marathon-des-sables-weather/https://runfast.tech/blog/marathon-des-sables-weather/Wed, 09 Sep 2026 08:00:00 GMTMarathon des Sables weather in April is hot, very dry and often windy by day, and cool at night. Afternoons in the Moroccan Sahara average about 29 °C (85 °F) and occasionally pass 35 °C (95 °F), with dew points usually below freezing. Nights fall to about 12 to 14 °C (54 to 57 °F). https://runfast.tech/blog/ultra-running-weather/https://runfast.tech/blog/ultra-running-weather/Tue, 08 Sep 2026 08:00:00 GMTUltramarathon weather is a whole day of weather, not one forecast. Plan for the cold dark start, the afternoon heat, the night and the heights you'll cross. At the Comrades Marathon in 2023, an 11-hour runner's feels like rose from 2.9 °C (37 °F) to 25.9 °C (79 °F) in one run.