Daily minimum temperature (overnight low), by month, latest 50 complete summers · ERA5 reanalysis via Open-Meteo
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Median overnight low by month, per year
Mean daily temperature amplitude by month (daily max − min)
Tropical nights per month (overnight low ≥ 20 °C), stacked
A "tropical night" stays at or above 20 °C all night — a standard heat-stress indicator (WMO / ECA&D). Bars stack June + July + August.
Tropical-night streaks per summer (≥ 2 consecutive nights ≥ 20 °C)
Decade summary by month (median night low)
Independent cross-check vs. nearest weather station (Meteostat)
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Method & data
Source: Open-Meteo Historical Weather API,
serving the ERA5 reanalysis (Copernicus / ECMWF), ~25–30 km grid. Place lookup uses Open-Meteo's geocoding API.
Each calendar month (June, July, August) is treated as a separate series; trend = ordinary least-squares regression of that month's median
daily-minimum temperature against year, slope reported per decade with a two-sided t-test (significant at p<0.05 when |t|>~2.0, df≈48).
A month is included only if ≥25 of its days are present. ERA5 is a model-observation blend — excellent for trends, not an exact single-station
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