🌍 The evidence, from the data

Is warming really happening?

We put the question to the test with data measured since 1940 in 107 Italian cities. No opinions: just temperatures, anomalies and trends.

🔎 Verdict on the data · Italy (city average)

🔥 Warming is confirmed

Comparing the two 30-year climate normals (the WMO standard), Italy (city average) went from an average of 13.31° in 1961–1990 to 14.31° in 1991–2020: a change of +1.00°C. The underlying trend (1940–2025) is +0.20°C per decade (±0.05, 95% confidence interval) and is a clear signal (R² = 0.45).

Between the two normals

+1.0°C

Per decade

+0.20°C

± 0.05 (95% CI)

Reliability (R²)

0.45

Series analyzed

1940–2025

The "warming stripes", 1940–2025

Each stripe is a year: blue = colder than the 1961–1990 normal, red = warmer. The dominant color, at a glance, tells how the temperature has changed over time.

194019501960197019801990200020102020

Annual anomaly vs 1961–1990

How much each year was warmer (red) or colder (blue) than normal. The dashed line is the underlying trend. The warmest year was 2022.

Average by decade

Aggregating by decade, the yearly noise disappears: the trend rises clearly and progressively.

🧪 Method and transparency

Source: ERA5 reanalysis from ECMWF / Copernicus via Open-Meteo — the scientific standard for reconstructing past climate (2 m air temperature, from 1940).
Anomalies, not absolute values: each year is compared against the 1961–1990 climate normal(the WMO reference period). Anomalies remove seasonal noise and make the underlying trend visible.
Trend: computed by linear regression on annual means; R² indicates how much of the data the line explains (0 = no trend, 1 = perfect trend).
Limitations: each city is a single point on the ERA5 grid. This data concerns these Italian cities (regional scale): it is consistent with the global warming measured by NASA, NOAA and Copernicus, but does not replace it.
No cherry-picking: the entire available series is always shown, from the first to the last year.
Daily records: exclude the last ~4 months. ERA5 publishes a preliminary version after a few days, but the final ("re-analyzed") version arrives later and can differ slightly: an absolute record is never declared on data that is still provisional.
Highs and lows: shown separately from the mean (same two-normal comparison) because days and nights don't always warm at the same rate.
Climate analog: compares this city's annual mean temperature with that of other monitored cities in past decades — not the full seasonal profile, which would require data not yet available at this level of detail.

❓ Q&A

Frequently asked about Italy's climate

How much has Italy warmed since 1940?

Two figures, both from the same data and measuring different things. +1.7°C is the linear trend over the whole series, from 1940 to today — this is the answer to "since 1940". +1.0°C is the gap between the two 30-year climate normals (1991–2020 minus 1961–1990), the WMO standard used across this site because it is the most robust to year-to-year noise; being a comparison between those two windows, it does not include the warming before 1961 or after 2020. Neither figure is the warming since the pre-industrial era (1850–1900), which this series does not cover and which is larger still. Source: ERA5 reanalysis (ECMWF/Copernicus), 107 cities.

Is Italy getting warmer?

Yes. Comparing the 1961–1990 and 1991–2020 climate normals, the average temperature of the monitored Italian cities rose by +1.0°C — measured data, not a projection.

🔥

Italia Rovente · loading data…

🔥 Warming is confirmed

Between the two normals

+1.0°C

Per decade

+0.20°C

± 0.05 (95% CI)

Reliability (R²)

0.45

Series analyzed

1940–2025

The "warming stripes", 1940–2025

Each stripe is a year: blue = colder than the 1961–1990 normal, red = warmer. The dominant color, at a glance, tells how the temperature has changed over time.

194019501960197019801990200020102020

🧪 Method and transparency

Source: ERA5 reanalysis from ECMWF / Copernicus via Open-Meteo — the scientific standard for reconstructing past climate (2 m air temperature, from 1940).

Anomalies, not absolute values: each year is compared against the 1961–1990 climate normal(the WMO reference period). Anomalies remove seasonal noise and make the underlying trend visible.

Trend: computed by linear regression on annual means; R² indicates how much of the data the line explains (0 = no trend, 1 = perfect trend).

Limitations: each city is a single point on the ERA5 grid. This data concerns these Italian cities (regional scale): it is consistent with the global warming measured by NASA, NOAA and Copernicus, but does not replace it.

No cherry-picking: the entire available series is always shown, from the first to the last year.

Daily records: exclude the last ~4 months. ERA5 publishes a preliminary version after a few days, but the final ("re-analyzed") version arrives later and can differ slightly: an absolute record is never declared on data that is still provisional.

Highs and lows: shown separately from the mean (same two-normal comparison) because days and nights don't always warm at the same rate.

Climate analog: compares this city's annual mean temperature with that of other monitored cities in past decades — not the full seasonal profile, which would require data not yet available at this level of detail.