Coldest Temperature Ever Recorded in the Amazon Rainforest: 3.9°C (39°F)

The Amazon is synonymous with heat and humidity — but it has a cold extreme. The lowest officially recorded temperature in the Amazon basin is 3.9°C (39.02°F), measured at Serra da Canastra National Park in Minas Gerais, Brazil, on July 1, 1975.

Why It Got That Cold

• Elevation: Serra da Canastra sits at ~1,200–1,500 m (3,900–4,900 ft) — part of the Brazilian Highlands on the Amazon's southern fringe.
• Radiative Cooling: Clear, dry winter nights (Southern Hemisphere July) allow rapid heat loss.
• Cold Air Drainage: Dense, cold air sinks into valleys where the station sits.
• Polar Air Intrusion: Occasional friagem events — Antarctic cold fronts surging north — drop temperatures basin-wide.

Context: This Is the Exception

The Amazon's typical range is 25–28°C (77–82°F) year-round. The 3.9°C record occurred at high elevation on the biome's edge. In the lowland core (e.g., Manaus, Iquitos), temperatures rarely dip below 18°C (64°F).

Ecological Impact of Cold Snaps

Even brief cold events (5–10°C) can:

• Damage cold-sensitive plants (many tropical species lack frost tolerance)
• Disrupt pollinator and frugivore activity
• Cause mortality in amphibians, reptiles, and insects
• Alter forest composition over time at elevation gradients

Climate Change Consideration

Paradoxically, climate change may increase cold extremes in some Amazon margins by disrupting atmospheric circulation (weakened Hadley cell, more frequent polar outbreaks). Meanwhile, the core warms steadily.

The Amazon isn't uniformly hot — its edges, elevations, and atmospheric dynamics create surprising thermal diversity. But 3.9°C remains a remarkable outlier in the world's largest tropical forest.