How bad Spanish heat waves (olas de calor) get

Key rules

• Heat wave: Only AEMET declares an ola de calor, and it needs at least 3 consecutive days of widespread extreme heat.
• Two systems: AEMET colour warnings and Ministry of Health heat-risk levels are separate and use different zones and thresholds.
• Local thresholds: The temperature that triggers a warning differs by zone, so check your own zone rather than a national number.
• Outdoor work: Outdoor work is banned during orange or red AEMET warnings when safety cannot be guaranteed.

A heat wave is an official event, not just a hot day

An ola de calor is declared by AEMET, Spain's state weather agency. It needs at least 3 consecutive days in which at least 10% of the chosen reference stations pass their own very high temperature limit. A hot week in your town may not count if the heat is not widespread enough.

Two other warning systems use colours

You will also see colour warnings that are not the same thing as a declared heat wave.

• AEMET colour warnings cover maximum temperature: green (no risk), yellow (some risk, be aware), orange (important risk, be prepared) and red (extreme risk, take action). The trigger temperature differs by warning zone. Most zones sit between the high 30s and the mid 40s °C.
• Ministry of Health heat-risk levels work separately. Spain is split into about 182 meteosalud zones, each with its own maximum and minimum temperature limits. The levels run from 0 (low, green) and 1 (low-medium, yellow) to 2 (medium, orange) and 3 (high, red). Level 3 brings the strongest alerts and extra protection for older people, babies and people with chronic illness. The system runs roughly from 1 June to 30 September, with forecasts several days ahead.

The same temperature can be a red warning in one zone and green in another. Check your own zone on the AEMET warnings map and the Ministry's heat-risk tool. The decision block below helps you pick which to follow.

How long and how hot

Most heat waves last from about 3 days to 2 weeks. Recent ones ran longer: August 2023 lasted about 17-18 days and August 2025 around 16 days. Peaks commonly reach 42-46 °C in the Guadalquivir, Guadiana and Ebro valleys and the Mediterranean interior. The record is 47.6 °C at La Rambla (Córdoba) in August 2021. In June 2025, El Granado (Huelva) hit 46.0 °C, a June record. Heat waves have become much more frequent since the 1980s. The Canary Islands have their own weather pattern, so these figures fit the mainland and the Balearics best.

How daily life changes

• Hours shift. People move activity to early morning and late evening and avoid 12:00-18:00. Streets and terraces fill after dark.
• Shops. Many small shops close for a long midday break, and some open late. The siesta is more common in the south.
• Work. Employers must protect workers from heat. Since 2023, outdoor work is banned during orange or red AEMET warnings when safety cannot be guaranteed. Many outdoor jobs start early instead.
• Schools. Most regions run to late June. Some have allowed flexible hours or heat-protection measures.
• Public spaces. Cities open climate shelters (refugios climáticos), and pools and air-conditioned public buildings stay open longer. Councils sometimes close parks or cancel events.

School hours, shelters and closures are set by regions and councils, so ask your town hall what applies where you live.

Choosing between options

Which heat warning should you follow today?

• AEMET warning colour: Use it for the weather itself: green means no risk, yellow means be aware, orange means be prepared and red means take action. It sets the rules for outdoor work.

• Ministry of Health heat-risk level: Use it to judge risk to your body and to vulnerable people such as older people, babies and people with chronic illness.

• Declared heat wave (ola de calor): Use it as the signal that the heat will last: at least 3 consecutive days with many stations above their normal hot-day limit.

Follow whichever is highest for your zone. If either shows orange or red, or level 2 or 3, change your daily routine and look after anyone vulnerable.

Timeline and deadlines

• A heat wave is declared once the heat has lasted at least 3 consecutive days across enough stations: from day 3 of the heat episode

• A typical Spanish heat wave ends: between about 3 days and 2 weeks after it starts

• The longest recent waves run well past the usual range: August 2025 lasted around 16 days and August 2023 about 17-18 days: in recent summers

What to watch out for

• Mixing up the two warning systems: A heat wave (ola de calor) is an officially declared event by AEMET, Spain's weather agency. The Ministry of Health's heat-risk levels are a separate system with their own thresholds for each of about 182 zones. You can be in a high health risk level with no heat wave declared. Check both your AEMET warning colour and your health-risk level for your zone before planning your day.

• Assuming one temperature fits all of Spain: The temperature that triggers a warning differs by zone. Most zones trigger in the high 30s to mid 40s °C, so 38 °C can be routine in one place and a warning in another. Look up your own zone's value instead of comparing with a friend in another region.

• Planning a normal day at midday: Peaks commonly reach 42-46 °C in the Guadalquivir, Guadiana, Ebro and Mediterranean interior areas, and the 12:00-18:00 period is the one to avoid. Small shops often close at midday, and councils sometimes close parks or cancel events. Do errands early morning or late evening, and check local announcements for closures.

• Expecting to work outdoors through an orange or red warning: Employers must protect workers from heat. Since 2023, outdoor work is banned during orange or red warnings when safety cannot be guaranteed. If you work outdoors, ask your employer how work is moved to early starts when a warning is issued.

Heat in Spain: quick answers

Can you get heatstroke at night?

Yes, heatstroke can happen at night, especially for older people, babies, people with chronic illness and anyone in a home that stays hot. The body cannot cool down when night temperatures stay high. Heavy sweating, dizziness, headache and nausea point to heat exhaustion, so move somewhere cooler and drink water.

How much water should you drink in a heat wave?

Adults typically need about 1.5-2 litres of water a day, and more if you sweat heavily or work outdoors. Drink often without waiting to feel thirsty, because thirst appears late. Avoid alcohol, caffeine and very sugary drinks, and ask a doctor if you take diuretics or have a fluid restriction.

Do fans still help when it is very hot?

Fans help at moderate temperatures, but they stop helping once the air is around 35 °C or above. Then try cool showers, wet cloths, shade or a cool public place instead. Do not point a fan at one person for long periods.

What do the weather warning colours mean?

The four heat warning colours are green for no risk, yellow for some risk, orange for an important risk and red for an extreme risk. The temperature that triggers each colour differs by warning zone, mostly from the high 30s to the mid 40s °C. A heat wave itself is at least 3 days in a row of unusually high maximum temperatures across many stations.

Do you need sunscreen in winter in Spain?

Not every day for most people on the mainland, but yes when the UV index is 3 or above, use SPF 30 or higher on exposed skin. The south and the Canary Islands can reach that level even in winter. Also wear it for skiing, high mountains, long outdoor activity or if you have fair skin.