ERA5 reanalysis · 48.12°N 17.10°E · 157 m · 27,759 daily records
Every day from 1 January 1950 to 31 December 2025, pulled from the Open-Meteo archive. The averages moved. The rain, mostly, did not.
01 — The annual signal
The 1951–1980 mean was 9.73 °C. The last ten years averaged 11.81 °C.
Fitted across the whole record, the trend runs +0.29 °C per decade — and almost all of it arrives after 1985.
1996 is the last year to come in more than a degree below the old normal; 2010 is the last to come in below it at all.
02 — Seasonal distribution
Each cell is a decade's average for that month, measured against the same 1951–1980 baseline.
Warming is not evenly spread. Winter and high summer move hardest; September and November move least.
The 1970s row is a useful reminder that a single decade can run cool in the middle of a warming record.
03 — Threshold days
Averages hide the part people feel. Threshold counts don't.
Days at or above 30 °C have gone from 7 a year to 23. Nights that never drop below 20 °C have gone from 2 to 13.
Frost is retreating more slowly than heat is arriving: 95 days a year down to 69.
04 — The shape of the year
The curve didn't change shape. It moved up in every month — but unevenly: +2.2 °C in January, only +0.4 °C in September.
January crossed zero: a month that used to average −2.2 °C now averages 0.0 °C, which changes what falls as snow and what falls as rain.
05 — The control
Mean annual precipitation is 624 mm, and the fitted trend is +5.5 mm per decade — well inside the year-to-year noise.
Worth keeping in the same page as the temperature charts: it's the honest contrast. A record can show a hard signal in one variable and nothing much in another.
Daily maximum, minimum and mean 2 m air temperature and precipitation totals for the grid cell containing Bratislava (48.12°N, 17.10°E, 157 m), 1950-01-01 to 2025-12-31, from the Open-Meteo Historical Weather API — an open, key-free interface to the ECMWF ERA5 reanalysis. 27,759 days, no missing values.
Anomalies are measured against the 1951–1980 monthly and annual means computed from the same series. Trends are ordinary least squares on annual means. All aggregation was done from the daily values; nothing here is a published summary statistic.
ERA5 is a reanalysis on a ~25 km grid, not a station record. It represents the average conditions over a grid cell, so it systematically smooths extremes: the hottest day in this dataset is 38.3 °C, while the Bratislava-Koliba and airport stations have recorded above 39 °C. Trends and counts are reliable; individual daily records are not.
Everything before 1979 comes from ERA5's preliminary back extension, a separately produced segment with fewer observations behind it and documented regional biases. The warm early 1950s in these charts should be read with that in mind; the post-1979 record is the solid part.
Precipitation in reanalysis is the weakest of these variables — modelled rather than closely constrained by observation. Treat the rainfall panel as "no clear trend", not as a precise total.
Built with Claude · data retrieved 21 August 2026