The short answer
Marathon 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).
Key takeaways
- Nearly half of early-April days in our ERA5 sample reached 30 °C (86 °F); the hottest, 36 °C (97 °F).
- Dew points near −4 °C (25 °F) let sweat evaporate, so you lose water fast.
- Calm air and midday sun lifted a hot day's WBGT from High to Extreme.
- Nights fall about 13 to 15 °C (24 to 27 °F) below the afternoon.
On this page
- What is Marathon des Sables weather like?
- How hot does the Sahara get in April?
- What does dry desert heat do to your body?
- How cold are the nights in the bivouac?
- How do wind and sand change the race?
- What weather does the long stage bring?
- How should you acclimatise for Sahara heat?
- How can you check the weather for each stage?
- Questions runners ask
- Sources and method
Words this guide uses
- Self-sufficiency
- At the Marathon des Sables you carry your own food, kit and sleeping bag for the week; the organiser provides water and tents.
- WBGT
- Wet-bulb globe temperature, a heat-stress number combining air temperature, humidity, sun and wind.
- Dew point
- The temperature at which the air would be saturated; the lower it is, the drier the air and the faster sweat evaporates.
- ERA5
- The Copernicus reanalysis of past weather, hourly, on a grid about 31 km (19 miles) apart.
What is Marathon des Sables weather like?
Marathon des Sables weather is desert spring: hot, very dry afternoons, cool nights and wind that moves sand. The race, now the MDS Legendary, crosses the southern Moroccan Sahara in six stages each April. Our ultra running weather hub covers other long races and multi-day runs.
The 40th edition ran its stages from 5 to 11 April 2026. You carry food, kit and sleeping bag; the organiser provides water and Berber tents. To see the heat on your own training loop, try Map your run.
| The race at a glance | MDS Legendary, Morocco |
|---|---|
| When | Early to mid-April; the 2027 programme runs 2 to 12 April |
| Distance | About 250 km (155 miles), six stages |
| Long stage | 80 to 90 km (50 to 56 miles) in 2025; 100 km (62 miles) in 2026 |
| Pack | 6.5 to 15 kg (14 to 33 lb) |
| Cut-off pace | 3.5 km/h (2.2 mph): 17:09 per km (27:35 per mile) |
| Organiser's April average | 30 °C (86 °F) by day, 14 °C (57 °F) at night |
How hot does the Sahara get in April?
About 26 to 30 °C (79 to 86 °F) on an average afternoon, with some days above 35 °C (95 °F). The nearest towns with WMO weather stations give the baseline.
| Place | April high, °C (°F) | April low, °C (°F) | May high, °C (°F) |
|---|---|---|---|
| Ouarzazate (WMO, 1991–2020) | 26.7 (80) | 11.9 (53) | 30.7 (87) |
| Errachidia (WMO, 1991–2020) | 26.1 (79) | 13.0 (55) | 30.3 (87) |
May is about 4 °C (7 °F) hotter, so an April race sits just before the real heat.
The open desert runs warmer. In hourly ERA5 reanalysis near Merzouga for 1 to 15 April, 2015 to 2024 (150 days), highs averaged 29.3 °C (85 °F). Nearly half reached 30 °C (86 °F), and the hottest, 8 April 2024, hit 36.0 °C (97 °F).
What does dry desert heat do to your body?
It lets sweat evaporate, so you cool well, but you lose water fast. At the warmest hour, the dew point averaged −3.8 °C (25 °F), with humidity near 12%.
That keeps WBGT, the heat-stress number race medics use, far below the air temperature. Wind and sun move it most (RunFast engine, clear sky).
| Afternoon | Air, °C (°F) | Dew point, °C (°F) | Wind, km/h (mph) | WBGT, °C (°F) | Heat stress |
|---|---|---|---|---|---|
| Typical, breezy | 29.3 (85) | −3 (26) | 18 (11) | 21.0 (70) | Moderate |
| Typical, calm | 29.3 (85) | −3 (26) | 5 (3) | 23.7 (75) | High |
| Hot, breezy | 36.0 (97) | −3 (26) | 22 (14) | 24.1 (75) | High |
| Hot, calm, midday | 36.0 (97) | −3 (26) | 5 (3) | 27.9 (82) | Extreme |
| Hot, humid air | 36.0 (97) | 20 (68) | 22 (14) | 30.6 (87) | Extreme |
The last row shows why humid heat at the same temperature is harsher. See WBGT for runners and running in heat and humidity.
The price is water. Racinais and colleagues (2015) put sweat rates in vigorous exercise in the heat at 1.0 to 1.5 litres an hour. At 8 km/h (5 mph), or 7:30 per km (12:04 per mile), 10 km (6.2 miles) between checkpoints takes 75 minutes: 1.3 to 1.9 litres of sweat.
The American College of Sports Medicine (2007) warns that exertional heat illness can strike anyone working hard in the heat. The race's medical team and rules override this article, which is not medical advice.
How cold are the nights in the bivouac?
Cool rather than cold: about 12 to 14 °C (54 to 57 °F). The trouble is the swing of 13 to 15 °C (24 to 27 °F) from the afternoon, onto a body that has sweated all day. A sleeping bag and survival sheet are compulsory, and every gram of warmth rides on your back for six stages.
How do wind and sand change the race?
Afternoon wind averaged 18 km/h (11 mph) in our sample. Gusts passed 50 km/h (31 mph) on 38 of 150 days and 60 km/h (37 mph) on 14.
If a sandstorm cuts visibility to zero, the rules say you stop. A breeze lowers heat stress, but a headwind in soft sand raises effort: see wind and hills.
What weather does the long stage bring?
All of it. The 2026 long stage ran 100 km (62 miles), the longest in the race's history, with a 40-hour limit. Most of the field started at 05:00.
At 4 km/h (2.5 mph), or 15:00 per km (24:08 per mile), you reach km 40 (mile 25) at 15:00, in the afternoon heat. Headlamps go on from 19:00, near km 56 (mile 35), and you finish near 06:00. Pack for 30 °C (86 °F) and 12 °C (54 °F) in one bag.
How should you acclimatise for Sahara heat?
Start about two weeks out. Racinais and colleagues (2015) ask for daily sessions of at least 60 minutes that raise core and skin temperature; most adaptations arrive within a week.
Train in dry heat if you can. Runners in South Africa or Australia reach April from summer; those in Britain, Europe or North America come out of winter and may need a heat room.
How can you check the weather for each stage?
Map each stage as one run in Map your run, up to 10 days ahead. Paces go to 25:00 per km (40:14 per mile), so walking works, and a 100 km stage fits.
Every kilometre shows feels like, dew point, WBGT and the weather cost at your pace. There's no multi-day tour yet; the fastpacking guide shows the one-day-at-a-time method. RunFast has no Sahara race-day history.
Questions runners ask
How hot does it get during the Marathon des Sables?
Most April afternoons in the region reach about 26 to 30 °C (79 to 86 °F). In ERA5 data for 1 to 15 April, 2015 to 2024, nearly half the days reached 30 °C (86 °F) and the hottest hit 36 °C (97 °F). Calm air and midday sun can lift WBGT heat stress to Extreme on a hot day.
How cold are Marathon des Sables nights?
Cool rather than freezing. April lows average 11.9 °C (53 °F) at Ouarzazate and 13.0 °C (55 °F) at Errachidia, and the organiser gives 14 °C (57 °F). It feels colder after a hot day, because the drop of 13 to 15 °C (24 to 27 °F) comes fast. A sleeping bag and survival sheet are compulsory.
How much water do you get at the Marathon des Sables?
Checkpoints about every 10 km (6.2 miles) refill you, and the 2026 rules give 5 litres (1.3 US gallons) at the end of each stage for the evening and next morning. Racinais and colleagues (2015) put vigorous sweat rates in the heat at 1.0 to 1.5 litres an hour, so drink to a plan.
Do sandstorms stop the Marathon des Sables?
They can stop you where you stand. The 2026 rules say that if a sandstorm cuts visibility to zero, competitors must stop. In our ERA5 sample for early April, gusts passed 50 km/h (31 mph) on about one day in four. A breeze lowers heat stress, but a headwind in sand costs effort.
How long should you heat acclimatise before the Marathon des Sables?
About two weeks of daily heat sessions. The 2015 consensus by Racinais and colleagues asks for at least 60 minutes a session, enough to raise core and skin temperature. Most adaptations come within the first week, and 6 to 10 days bring near-complete heart and sweat changes. Train in dry heat if you can.
Can you get a weather forecast for each Marathon des Sables stage?
Yes, once you have the stage's route and it's within 10 days. Map each stage as its own run at your walking or running pace, and read the feels like, dew point and WBGT for every kilometre. RunFast has no Sahara race-day history, so this is forecast only.
See the heat at your pace.
Drop in your route (GPX, FIT or TCX), pick the day and your pace, and see the feels like, dew point and heat stress for every kilometre, timed to when you’ll be there. Free, in your browser, no sign-up.
Sources and method
- Marathon des Sables (2026). MDS Legendary (format, distance, stages, self-sufficiency, cut-offs)
- Marathon des Sables (2026). Marathon des Sables Legendary 40th edition race regulation 2026
- Marathon des Sables (2026). MDS Legendary 2027 (dates, stages, water, checkpoints)
- Marathon des Sables (2026). Stage 4, MDS Legendary (the 100 km stage, 2026)
- Marathon des Sables (2026). Stage 3, 40th edition of the MDS Legendary (the 40-hour limit)
- World Meteorological Organization, World Weather Information Service (2023). Ouarzazate climatological information, 1991–2020
- World Meteorological Organization, World Weather Information Service (2023). Errachidia climatological information, 1991–2020
- Copernicus Climate Change Service (ECMWF) (2023). ERA5 hourly data on single levels from 1940 to present
- Open-Meteo (2026). Historical weather API (ERA5)
- British Journal of Sports Medicine (2015). Consensus recommendations on training and competing in the heat (Racinais et al.)
- American College of Sports Medicine (2007). Position stand: exertional heat illness during training and competition (Armstrong et al.)
- Journal of Occupational and Environmental Hygiene (2008). Modeling the wet bulb globe temperature using standard meteorological measurements (Liljegren et al.)
Race facts come from the organiser's own pages: the MDS Legendary format page, the 2026 race regulation, the 2026 stage reports and the 2027 event page. Town climate is the WMO World Weather Information Service's 1991–2020 normals for Ouarzazate and Errachidia (mean daily maximum and minimum). The desert sample is hourly ERA5 reanalysis (Copernicus Climate Change Service, ECMWF), read through Open-Meteo's historical weather API, for 1 to 15 April in each year from 2015 to 2024 (150 days) at the grid point at 31.0° N, 4.0° W, near Merzouga, about 690 m (2,260 ft) up. Highs are each day's warmest hour; dew point and humidity are taken at that hour; afternoon wind is the mean of 12:00 to 16:00 UTC; gusts are each day's highest modelled gust. ERA5's night lows at this point read several degrees warmer than the town stations, so we give night temperatures from the WMO normals instead. The worked examples use the RunFast engine: WBGT by Liljegren et al. (2008) at 700 m (2,300 ft), clear sky on 8 April, with the sun 45° up (mid-afternoon) or 66° up (midday), and the 10 m wind given. The typical rows use the sample's mean high and its humidity at that hour (12%); the hot rows use 8 April 2024 (humidity 8%, afternoon wind 22 km/h, 14 mph); the humid row keeps that day's air and wind with a 20 °C (68 °F) dew point. The long-stage timings assume an even 4 km/h (2.5 mph) from a 05:00 start. WBGT levels: Low below 18.3 °C (65 °F), Moderate to 22.8 °C (73 °F), High to 27.8 °C (82 °F), Extreme above, judged on unrounded values. Fahrenheit values are our conversions. RunFast is independent of the Marathon des Sables.
Wes Thomson
Wes Thomson builds RunFast, which times the heat, humidity and dew point to a runner's own pace along the route, and its sister Windline, live wind forecasts for cyclists. Both run on the same forecast engine. He writes these guides with one focus: what the weather will do to your run, kilometre by kilometre, and how to plan around it.