Spain September Heat: AEMET Forecast U-Turn and 43C Heat 2026

Spain September heat is making headlines as AEMET, the national weather agency, has dramatically revised its forecast. Initially expecting a calm start to September, AEMET now warns of temperatures soaring to 43°C in parts of the country, just days after a record low of -0.1°C was recorded in Ávila.

This sharp contrast—from near-freezing to scorching heat in less than a week—highlights the volatility of weather patterns and the challenges of long-term forecasting. Here's what happened, why it matters, and what to watch next.

What Happened: AEMET's Forecast U-Turn

On August 21, AEMET's bulletin predicted that the first week of September would be "around usual values" for the time of year. By August 27, the agency had revised its outlook, warning of "high temperatures for the season" across most of Spain.

The change came after new weather models showed a strong high-pressure system, often called a "heat dome," settling over the region. This dome traps hot air near the surface, causing temperatures to spike.

The most striking example: on Friday, August 28, Puerto del Pico in Ávila recorded -0.1°C. The following Thursday, September 3, the countryside of Córdoba is expected to hit 43°C. That's a swing of over 40 degrees in just six days and less than 300 kilometers.

Why It Matters: Rare September Heat

Heat waves in September are uncommon in Spain. As summer wanes, days get shorter, and the sun's intensity decreases, making extreme heat less likely. AEMET has stopped short of calling this a "heat wave," instead issuing a yellow warning for 38°C in the Córdoba countryside.

Even if temperatures reach 43°C in some southern areas—which is quite possible—it won't be as extreme as the heat waves of July and August. The agency notes that while a heat wave can't be ruled out, it's difficult because the days are shortening.

Key Takeaways

• AEMET initially expected a calm September but now forecasts temperatures up to 43°C.
• The shift is due to a heat dome forming over Spain, trapping hot air.
• September heat waves are rare because of shorter days and weaker sun.
• AEMET has issued a yellow warning for 38°C in Córdoba, avoiding the term "heat wave."
• The strong temperature contrast—from -0.1°C to 43°C in six days—shows how quickly weather can change.

Who Is Affected: Southern Spain Braces for Heat

The heat will be most intense in southern Spain, particularly the Guadalquivir Valley and parts of Andalusia. Cities like Córdoba, Seville, and Granada could see temperatures well above 40°C.

Residents and visitors should take precautions: stay hydrated, avoid outdoor activities during peak hours, and check on vulnerable neighbors. The heat could also strain energy systems as demand for air conditioning rises. The background to this story is set out in Spain's AEMET Forecast: No Autumn in Sight as Heat Persists. A related thread runs through Spain Heatwave: New Temperature Surge Expected in Late September. Earlier coverage in Australia September Heatwave: Hottest Day in Years Forecast shows how the argument developed.

What to Watch Next: Heat Dome and Beyond

The heat dome is expected to persist through the first week of September, with the potential for high temperatures to extend until around September 20. However, as autumn progresses, the intensity should gradually decrease. A closer look at the same subject appears in Europe Weather Forecast: Rain and Temperature Drop Ahead. Anyone following the wider picture can start with Spain France Heatwave Wildfires: Complex Days Ahead with Risks. The same theme surfaces in Spain Heatwave and Wildfire Risks: What Travelers Must Know, which takes a different angle.

AEMET will continue to monitor the situation and update its forecasts. While this event may not be classified as a heat wave, it serves as a reminder that extreme weather can occur outside the typical summer months. Context on how this played out before sits in Australia Weather: Severe Storms and Flash Flooding Forecast. A companion piece, How Meteorologists Recreated the D-Day Weather Forecast, approaches the same subject from another angle.

Comparison of Forecasts