August 2025, the third-warmest August on record globally

August 2025 cemented its place in the climate record books. New global analyses show last month ranked as the third-warmest August ever observed, continuing an extended period of exceptional heat across land and ocean. The planet’s average surface air temperature for the month is estimated at 16.60°C—0.49°C above the 1991–2020 average and 1.29°C warmer than the 1850–1900 pre-industrial benchmark.

What the numbers tell us

• Global average surface air temperature in August 2025: 16.60°C
• Departure from the 1991–2020 August average: +0.49°C
• Departure from the 1850–1900 pre-industrial level: +1.29°C
• Ranking: Third-warmest August on record globally

These figures reflect the ongoing warming of the climate system. Half a degree above the late-20th-century average may sound small, but at a planetary scale it points to amplified heat extremes, warmer nights, and a greater likelihood of prolonged hot spells.

A fierce mid-month heatwave in Europe

From 8 to 18 August, Europe endured a searing heat episode marked by widespread, persistent high temperatures. Daytime maximums surged across large swaths of the continent, while nights offered little relief. Analyses of daily average conditions during that period reveal two complementary perspectives:

• Average daily maximum temperatures: A map of this metric highlights the intensity of daytime heat, with hotspots stretching from southern to central Europe.
• Temperature anomalies relative to 1991–2020: A companion view of daily mean anomalies shows how unusual the warmth was compared to recent decades, illuminating regions where temperatures ran far above typical mid-August values.

Together, these views illustrate not only how hot it felt during the afternoons, but also how substantially the entire 24-hour cycle skewed warmer than normal. Such compounding heat—high daytime peaks paired with elevated nighttime lows—can intensify stress on ecosystems, agriculture, and public health.

Why this August matters

Crossing well above the 1991–2020 average and more than a degree above pre-industrial levels underscores the broader trajectory of planetary warming. Each additional fraction of a degree raises the odds of extreme events. The August signal is consistent with recent patterns: warmer baseline conditions are priming the atmosphere for more frequent and intense heatwaves, even in regions accustomed to summer warmth.

The European heatwave offers a stark on-the-ground example. Elevated baseline temperatures tend to lengthen hot spells, increase the likelihood of record-breaking days, and reduce the window for nighttime cooling. When nights stay warm, heat stress accumulates, challenging energy systems, straining water resources, and testing urban infrastructure designed for cooler norms.

Looking ahead

As the year progresses, global temperature rankings will hinge on both short-term variability and the entrenched long-term trend. While month-to-month fluctuations are expected, the consistent climb relative to historical baselines remains the defining feature. Monitoring how frequently monthly averages exceed the 1991–2020 norm—and by how much—will be crucial for anticipating pressure points across sectors from agriculture to public health.

August 2025 serves as another waypoint in a warming world: a month that was notably hot by recent standards and markedly hotter than the pre-industrial past, punctuated by a European heatwave that exemplified the risks of sustained, compounding heat. The signal is clear; the stakes are rising with every warm month that resets expectations for “normal.”