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Rank 17 of 80

Mainz

19.3 hot days a year, average 2016–2025. In 1951–1960 it was 7.3.

Grid and weather station typically differ by about 0.9 days. If the value is shifted by that much, the city lies on one of the places 15 to 20. How it was checked.

Mainz has no historical counterpart: no major German city was as hot in 1951–1960 as Mainz is today.

19.3Hot days today
7.3Hot days 1951–1960
32.3hottest year: 2003
10 → 17Rank then and now
45.22026, provisional

2026: 45.2 hot days up to the cut-off date – 2.3 times the decade average. This puts Mainz above its previous record year 2003 (32.3 days). The count covers the first 292 days of the year, up to 19 October. The year is therefore not yet complete, and the figure comes from the daily grid rather than the annual grid, which the DWD only publishes after the end of the year. Over the three most recent years available in both, the two agree on average (+0.18 days); for a single city they typically differ by 1.5 days, in individual cases by up to 6.8. This figure is not included in any decade average or any rank on this page.

010203040195119882025
010203040195119882025
1951–2025, axis 0 to 46 days. Grey: the national median. The same axis as on every other city page – the lines can be compared with one another.

Decade by decade

PeriodHot daysRank
1951–19607.310
1961–19707.715
1971–19809.26
1981–19909.210
1991–200015.43
2001–201016.56
2006–201512.624
2016–202519.317

Context

This figure describes the location of Mainz. No city administration decides on location. On shade over streets, schoolyards and playgrounds, it does.

What can be changed

Location is fixed, the residential surroundings are not

36.0 %of the residential surroundings is tree cover
Rank 41of 80 for green where people live

This measures the share of residential surroundings covered by trees – from the satellite, weighted by the population of the same 100 m cells as the heat figure above. Both figures therefore apply to the same places and can stand side by side. Parks, cemeteries and gardens count. The city’s stock of street trees requires the tree register.

Examples in the same location

Cities with a similar number of hot days and a similar size to Mainz that have clearly more green where people live:

  1. Mainz19.3 days36.0 %
  2. Potsdam18.7 days43.7 %

Hot days per year, average 2016–2025, and green where people live. Compared are cities no more than 1.5 hot days apart, at most three times as large or as small, with at least 5.0 percentage points more green. Green also depends on urban form and topography; the comparison shows what occurs in the same location and is not a grade for any administration.

Heat action plan

Mainz has a published heat action plan: „Hitzeaktionsplan der Landeshauptstadt Mainz „Mensch und Gesundheit““ (2026).

Research as of 24 October 2026. Corrections and tips to kontakt@julianzuber.de.

The map for this city

For Mainz this has been analysed across the city area: trees, land, climatopes. deutschland-hitzesicher.de/mainz-hitzesicher (in German)

Each city has its own access to its map. Enquiries to kontakt@julianzuber.de.

Neighbours in the ranking

  1. 15Saarbrücken19.5
  2. 16Trier19.5
  3. 17Mainz19.3
  4. 18Dresden19.1
  5. 19Potsdam18.7

Hot days per year, average 2016–2025. All 80 at a glance