# Extreme heat and low humidity in Piauí

> Live situation record from CLSTR: https://clstr.news/situations/extreme-heat-and-low-humidity-in-piau
> Updated: 2026-09-14T22:58:00.000Z. Sources: 7. Developments: 2.

The Brazilian state of Piauí has experienced a period of extreme heat and critically low humidity. Initially, the Secretariat of Environment and Water Resources (Semarh) issued alerts due to a high-pressure atmospheric system that inhibited cloud formation, raising temperatures toward 40°C and creating a significant risk of forest fires.

By mid-September, the heatwave persisted with cities such as Castelo do Piauí, Oeiras, and Piripiri recording temperatures exceeding 40°C. The region has also seen intense temperature fluctuations; for example, Oeiras recorded a high of 40.7°C followed by a low of 15.6°C. Humidity levels remained dangerously low, with some areas dropping to 12%.

## Timeline

### 2026-09-14: Piauí cities record extreme heat and temperature swings

Cities in Piauí, Brazil, are experiencing extreme heat and temperature swings, with Oeiras recording 40.7°C and dropping to 15.6°C within 24 hours due to a hot, dry air mass.

3 sources. https://clstr.news/cluster/piau-cities-record-extreme-heat-and-temperature-swings

### 2026-08-26: Piauí faces extreme heat and high forest fire risk

Piauí faces extreme heat up to 40°C and humidity as low as 10%, triggering Semarh alerts for increased forest fire risks due to a high-pressure atmospheric system.

4 sources. https://clstr.news/cluster/piau-faces-extreme-heat-and-low-humidity-levels

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Cite as: Extreme heat and low humidity in Piauí. CLSTR, https://clstr.news/situations/extreme-heat-and-low-humidity-in-piau