“The results indicate that extremes in heat-related metrics for daily T [Max] in the summer have not increased and in fact often show modest declines since 1899, due mostly to the early heat events during 1925-1954.”  – Christy, 2026

The contiguous United States (CONUS) has the most reliable and comprehensive long-term daily maximum and minimum temperature records, with over 1,200 stations recording these data since the late 19th century.

It is often reported that extremes in hot and cold temperatures – and especially heatwaves – have been increasing in both frequency and intensity in the last few decades as a consequence of rising greenhouse gas concentrations.

However, reliable data from temperature stations across the CONUS indicate extreme heat, extreme cold, and heatwave duration and intensity have been declining since 1899, due mostly to the much higher extremes recorded during the 1925-1954 period.

Conveniently, most alarmist claims about accelerating maximum and minimum temperature extremes start their analysis in the 1950s or later.

In recent decades, CONUS extreme heat (and cold) records fall well within the range of natural variability.

“The metrics for extreme summer heat, e.g., hottest values, number of heatwave days, etc., show modest negative trends since 1899. Extreme cold temperature metrics also indicate a decline in their occurrences especially since the 1990s. In sum, instances of both hot and cold extreme metrics have declined since 1899.”

“[T]he heat extremes occurring in the CONUS today are well within the range that natural variability already provides.”

“[T]here is no increase in the occurrence of 95°F (35°C) days within the CONUS, and in fact, the CONUS has experienced an 8.3% decline since 1899. None of the past 10-year totals [2015-2025] are in the top ten values.”

Image Source: Christy, 2026