Marathon des Sables Weather Guide: Complete Guide to Sahara Desert Running

The Marathon des Sables—six days and approximately 250 kilometers across the Sahara Desert—is often called "the toughest footrace on Earth." While that title is debatable among ultrarunners, what's not debatable is the weather challenge. Runners face daytime temperatures that can exceed 120°F, nighttime temperatures that can drop to 50°F, blinding sandstorms, relentless sun, and the constant, inescapable reality of being in one of Earth's most hostile environments. The weather isn't a factor at the Marathon des Sables; it is THE factor.

This guide covers everything about Marathon des Sables weather: the extreme conditions you'll face, how the Sahara's climate creates such challenges, the daily weather pattern, the feared sandstorms, and how to prepare your body and gear for this ultimate test of desert running.

Understanding Sahara Desert Weather

The Sahara Climate

What makes this desert extreme:

Why the Sahara is so hot:

Largest hot desert on Earth (over 3.5 million square miles)
Minimal vegetation to moderate temperatures
Clear skies allow maximum solar radiation
Sand absorbs and radiates heat
No humidity to create cooling effect

The extremes:

Highest recorded air temperatures on Earth occur in Saharan regions
Ground temperatures can exceed 150°F
Direct sun radiation is among the strongest anywhere
UV index reaches maximum levels
This is heat on a scale most runners have never experienced

The MDS timing:

Race held in April (usually)
Spring in the Northern Hemisphere
But spring in the Sahara is already extreme
Chose to avoid the absolute worst of summer
Still brutally hot by any standard

Race Location Specifics

Where the Marathon des Sables happens:

Southern Morocco:

The race takes place in the Moroccan Sahara
Varied terrain: rocky, sandy, mountainous
Elevation varies from flat desert to small mountains
The specific course changes each year
But the climate is consistently extreme

Typical race week conditions:

Daytime highs: 90-120°F (32-49°C)
Nighttime lows: 45-65°F (7-18°C)
Humidity: Very low (often below 20%)
Sun: Relentless during the day
Wind: Frequent, sometimes severe

The Daily Weather Pattern

Morning: The Start Window

When running is "easiest":

Early morning conditions:

Coolest time of day (relatively speaking)
Temperatures might be 60-75°F at dawn
Sun is low, shadows still exist
This is when stages begin
The window for comfortable running is brief

The race starts:

Stage starts are timed to maximize cool running
Usually early morning
But even early morning is warming
Runners must maximize progress during cool hours
This is strategy, not comfort

The transition:

Temperature rises rapidly after sunrise
By mid-morning, it's hot
Shade disappears
The desert reveals itself
The real race begins

Midday: The Brutality Zone

When conditions peak:

Peak heat:

Usually 11 AM to 4 PM
Temperatures regularly exceed 100°F
Ground temperature is significantly hotter than air
Heat radiates up from sand/rock
Standing in sun is dangerous

What this feels like:

The air itself feels hot to breathe
Eyes dry out
Skin burns despite sunscreen
Every step is effort
Time seems to slow

Running in peak heat:

Pace plummets
Some runners walk during hottest hours
Hydration becomes critical
Heat illness risk is maximum
Many runners rest during midday if stage allows

Afternoon: The Grinding Hours

When heat meets fatigue:

Afternoon conditions:

Still extremely hot
Runners are now fatigued and dehydrated
Wind often picks up
Dust and sand add to misery
The hardest hours psychologically

The combination:

Hours of running plus hours of heat
Cumulative dehydration despite drinking
Sun exposure compounds
The finish seems impossibly far
This is where MDS breaks people

Getting through:

Steady forward progress
Relentless hydration
Mental mantras
Breaking remaining distance into segments
Knowing evening eventually comes

Evening and Night: Relief and Recovery

When temperatures finally fall:

Sunset:

Temperatures begin to drop
The change is noticeable and welcome
Finishing a stage in evening is a relief
But runners are now exhausted
Recovery begins but conditions are still extreme

Night conditions:

Temperature drops can be dramatic
From 100°F+ to 50-60°F overnight
This range (40-50 degrees) is challenging
Need to switch from cooling to warming
The desert night is cold by contrast

Camp life:

Bivouac tents in open desert
Sleeping on sand
Temperatures continue to drop
May need sleeping gear
Recovery is affected by cold nights

The Feared Sandstorms

Understanding Desert Storms

The khamsin and its effects:

What the khamsin is:

Saharan wind that carries sand and dust
Can occur rapidly and with little warning
Reduces visibility to meters
Wind can exceed 50 mph
Sand gets into everything

How sandstorms form:

Pressure systems create wind
Wind picks up surface sand
Sand accumulates in air
Wall of dust/sand advances
Can cover hundreds of miles

When they occur:

More common in spring (MDS timing)
Can happen any time but usually afternoon
May last hours or pass quickly
Unpredictable by nature
Part of desert reality

Running in Sandstorms

When the weather turns hostile:

Immediate effects:

Visibility drops dramatically
Sand gets in eyes, nose, mouth
Breathing becomes difficult
Navigation becomes challenging
Pace slows to a crawl

Physical impact:

Sand abrades exposed skin
Eyes require protection
Respiratory stress
Heat may actually drop (sand blocks sun)
But wind adds its own challenge

Safety protocols:

Race organization monitors conditions
Stages may be modified or stopped
Runners may be held until conditions pass
Following course markings is critical
Don't try to push through truly dangerous conditions

Gear for Sandstorms

Protection essentials:

Eye protection:

Goggles (not just sunglasses)
Must seal against fine sand
Anti-fog features help
Carry these accessible, not buried in pack
Eyes are incredibly vulnerable

Respiratory protection:

Buff or face covering
Must filter sand while allowing breathing
Practice breathing through fabric
Wet fabric filters better but is uncomfortable
Have backup face coverings

Skin protection:

Cover exposed skin if possible
Long sleeves despite heat
Sand abrasion is real
Lips crack in sandy wind
Protection now beats treatment later

Temperature Management

The Heat Challenge

Managing extreme daytime temperatures:

Why MDS heat is different:

Sustained exposure over six days
Self-supported means carrying your water
No escape to air conditioning
Continuous stress without recovery
Cumulative effects compound

Heat illness at MDS:

Heat exhaustion is common
Heat stroke is a real risk
Medical staff are present but resources are limited
Prevention is essential
Recognizing early warning signs is critical

Cooling strategies:

Drink constantly (2+ liters per hour in peak heat)
Wet head and neck when water permits
Seek any available shade
Reduce pace dramatically in heat
Don't fight the conditions

The Cold Challenge

Managing nighttime temperature drops:

The forgotten challenge:

Most preparation focuses on heat
But nights can be surprisingly cold
The temperature swing is the challenge
Gear for 120°F day must also work for 50°F night
Many runners underestimate this

Night running stages:

One stage includes significant night running
Must carry extra layers for this
Running generates heat but pace may be slow
Stopping means getting cold quickly
Balance is critical

Sleep and recovery:

Sleeping cold affects recovery
Light sleeping bag or blanket needed
But weight is precious (self-supported race)
Finding the balance is personal
Test your sleep system before the race

The Temperature Swing

Managing 60-70°F daily changes:

The challenge:

Mornings can be cold (60s°F)
Midday can be hot (100s°F+)
Evenings cool rapidly
Nights may be cold (50s°F)
All in 24 hours

Gear implications:

Need layers for cold
Need minimal coverage for heat
Quick-changing capability
Light weight despite range
Everything you carry, you carry the whole race

Body adaptation:

This range stresses thermoregulation
Body constantly adjusting
Sleep quality affected
Energy expenditure increased
Cumulative fatigue from temperature alone

Preparing for MDS Weather

Heat Acclimatization

Building heat tolerance before the race:

The science:

Heat acclimatization takes 7-14 days of exposure
Body adapts: Better sweating, lower heart rate, expanded blood volume
Adaptations fade if exposure stops
Must maintain acclimatization until race
Doing this properly is critical

Practical approaches:

Train in heat (obvious but important)
Sauna exposure can help
Hot yoga as supplement
Treadmill in warm room
Get creative if you live in a cold climate

Timing:

Begin acclimatization 2-4 weeks before race
Final 2 weeks should include significant heat exposure
Don't let adaptations fade before travel
Continue exposure during travel if possible
Arrive with heat tolerance intact

Testing Gear in Conditions

Ensuring equipment works:

What must be tested:

All clothing in heat
Footwear (gaiters essential for sand)
Eye protection
Hydration systems
Sleep system

How to test:

Run long in hot conditions wearing race gear
Practice eating and drinking your race nutrition
Sleep in your sleep system
Test sand/dust protection if possible
Nothing new on race day (week)

Common failures:

Chafing in unexpected places
Footwear that fails in sand
Goggles that fog
Nutrition that doesn't work in heat
Discover these in training, not racing

Mental Preparation

Preparing for the psychological challenge:

What heat does mentally:

Reduces cognitive function
Increases irritability
Makes everything feel impossible
Creates despair
Tests will to continue

Building mental tolerance:

Train in discomfort regularly
Practice continuing when you want to stop
Develop mantras and mental strategies
Understand that the suffering is temporary
Connect to your "why"

The MDS mindset:

Accept that this will be hard
Pain is expected
Finishing is the goal
Each day is a victory
The experience is worth the suffering

The MDS Weather Experience

What It's Actually Like

From those who've done it:

Day 1:

The heat shock—even with preparation
Realizing this is real
The first experience of MDS sun
Wonder what you've gotten into
But you're still strong

Mid-race:

Heat becomes your constant companion
You stop noticing some things
You notice others more acutely
Time has a different quality
The days blur together

Final stages:

Exhaustion meets continued heat
The marathon stage in desert heat
Knowing the end is coming
Finding reserves you didn't know you had
The final push

The Transformation

What weather extremes teach:

Physical lessons:

Your body is capable of more than you knew
Heat can be survived
You are adaptable
Limits are flexible
Recovery is remarkable

Mental lessons:

You are tougher than you thought
Circumstances don't determine outcomes
Attitude is everything
Shared suffering creates bonds
You carry this confidence forward

Key Takeaways

Daytime heat is extreme. Temperatures of 100-120°F are normal; prepare for sustained heat exposure.
Nighttime cold is real. Temperature swings of 60-70°F require gear for both extremes.
Sandstorms happen. Eye and respiratory protection aren't optional; carry them accessible.
Heat acclimatization is essential. 2-4 weeks of heat exposure before the race is critical.
Hydration is constant. You'll drink 2+ liters per hour in peak heat; this is not optional.
Test all gear in heat. Everything you'll use must be proven in hot conditions.
Pace for conditions. Your pace in MDS heat will be far slower than normal; accept this.
Mental preparation matters. The heat affects your mind; prepare psychological strategies.

Marathon des Sables represents extreme heat running at its ultimate. Run Window can help you prepare for hot-weather running at home, but MDS requires dedicated heat acclimatization and specialized preparation.