Processed seasons

Every season the pipeline has analysed, side by side. "Heat burden" is area·days: a million km² in heatwave for ten days and ten million for one day score the same, which is the point — it measures how much heat there was, not how dramatic any single day looked.

Total heat burden by season

Season	Events	km²·days	Longest	Peak area	Max anomaly	Domes
2026	25	139.35 M	45 d	2.16 M km²	+19.8 °C	12
2025	25	136.23 M	70 d	1.75 M km²	+16.8 °C	14
2024	21	169.36 M	87 d	2.71 M km²	+16.7 °C	8
2023	27	115.47 M	29 d	2.63 M km²	+17.0 °C	11
2022	32	117.31 M	29 d	2.20 M km²	+19.4 °C	9
2021	31	106.61 M	31 d	2.64 M km²	+22.7 °C	11
2020	27	93.80 M	26 d	2.29 M km²	+16.9 °C	7
2019	23	85.66 M	25 d	1.84 M km²	+19.7 °C	6
2018	25	102.16 M	35 d	2.46 M km²	+18.7 °C	11
2017	21	78.76 M	21 d	1.96 M km²	+15.1 °C	9
2016	27	63.09 M	18 d	1.90 M km²	+15.6 °C	10
2015	21	99.94 M	32 d	1.89 M km²	+17.6 °C	11
2014	20	70.14 M	26 d	2.33 M km²	+19.1 °C	6
2013	23	67.13 M	20 d	1.78 M km²	+18.8 °C	10
2012	24	91.46 M	32 d	1.76 M km²	+14.9 °C	10
2011	23	52.71 M	18 d	1.21 M km²	+17.6 °C	14
2010	18	113.61 M	57 d	2.27 M km²	+20.1 °C	8
2009	19	31.24 M	16 d	815k km²	+13.6 °C	10
2008	18	40.59 M	15 d	2.31 M km²	+14.2 °C	8
2007	22	95.55 M	22 d	2.89 M km²	+15.2 °C	9
2006	35	99.82 M	23 d	1.50 M km²	+16.3 °C	17
2005	18	43.59 M	14 d	2.29 M km²	+15.9 °C	8
2004	15	29.86 M	15 d	1.68 M km²	+16.6 °C	8
2003	24	92.10 M	28 d	1.99 M km²	+15.9 °C	14
2002	18	64.09 M	27 d	1.40 M km²	+15.5 °C	5
2001	19	49.55 M	27 d	1.81 M km²	+16.0 °C	5
2000	26	51.14 M	19 d	1.64 M km²	+15.6 °C	14
1999	27	59.96 M	16 d	1.68 M km²	+15.3 °C	15
1998	20	51.84 M	22 d	1.60 M km²	+16.0 °C	7
1997	18	44.81 M	33 d	1.19 M km²	+15.3 °C	12
1996	13	49.20 M	17 d	1.86 M km²	+13.8 °C	8
1995	18	45.08 M	18 d	1.61 M km²	+19.4 °C	12
1994	20	61.73 M	26 d	2.20 M km²	+14.0 °C	11
1993	13	14.86 M	12 d	561k km²	+15.8 °C	8
1992	12	36.66 M	31 d	1.72 M km²	+18.3 °C	7
1991	15	20.16 M	16 d	877k km²	+14.4 °C	7

This is not a trend. These seasons happen to be contiguous, but a handful of years cannot establish a trend either. Every row uses the same 1991–2020 baseline, which makes the rows comparable with each other — and makes each one smaller than the same event measured against an earlier climatology, because that baseline already contains much of the warming since.

A season still inside the ERA5 latency window is incomplete: its last days are missing and its final events may still be running, so its burden is a floor and not a total. The season's own page says whether that applies. Domes are blank where a season has not been classified.

Method

ERA5 daily maximum 2 m temperature over land, against the 1991–2020 climatology (p90 in a centred 15-day window). A heatwave cell is Tx above p90 on at least 3 consecutive days.

ERA5 is a smooth reanalysis and under-states extreme station maxima. Extent, duration, structure and tracks come from here; absolute peak temperatures should be quoted from E-OBS or station records, not from this page.