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Paris · September · relief from the heat

Coolest places to go from Paris in September

In September, the coolest well-known place within 15 hours of Paris is Reykjavik, Iceland, 10.0 °C cooler than Paris and 6.3 h sun a day, about 6h 30m each way by air. Without flying, it is Dundee, United Kingdom, 5.1 °C cooler than Paris, about 11h 36m each way by train, for about 10× less carbon (56.9 kg CO₂e return against 561 kg).

The 10 coolest places within 15 hours of Paris

Ranked on relief from the heat in September alone, among well-known places (a Wikivoyage travel guide and at least 40,000 Wikipedia readers a year), one per area and at most three per country. The carbon is shown, not used to choose: the list further down is the other question, how much relief from the heat each extra kilogram buys.

  1. Reykjavik, Iceland10.0 °C cooler · 6.3 h sun a day · 3.5 mm rain a day · sea 10.8 °Cair ≈ 6h 30m · 561 kg CO₂e return
  2. Tromsø, Norway7.8 °C cooler · 4.9 h sun a day · 5.2 mm rain a dayair ≈ 6h 48m · 623 kg CO₂e return
  3. Östersund, Sweden6.8 °C cooler · 7.7 h sun a day · 2.6 mm rain a dayair ≈ 5h 48m · 443 kg CO₂e return
  4. Bodø, Norway6.6 °C cooler · 5.2 h sun a day · 6.6 mm rain a day · sea 13.0 °Cair ≈ 6h 24m · 543 kg CO₂e return
  5. Rovaniemi, Finland6.3 °C cooler · 6.0 h sun a day · 3.5 mm rain a dayair ≈ 6h 42m · 597 kg CO₂e return
  6. Trondheim, Norway5.7 °C cooler · 7.0 h sun a day · 5.8 mm rain a dayair ≈ 5h 48m · 426 kg CO₂e return
  7. Sundsvall, Sweden5.2 °C cooler · 8.4 h sun a day · 2.3 mm rain a day · sea 14.2 °Cair ≈ 5h 54m · 444 kg CO₂e return
  8. Luleå, Sweden5.2 °C cooler · 7.7 h sun a day · 2.4 mm rain a day · sea 14.3 °Cair ≈ 6h 24m · 550 kg CO₂e return
  9. Dundee, United Kingdom5.1 °C cooler · 7.7 h sun a day · 2.0 mm rain a day · sea 13.9 °Crail ≈ 11h 36m · 56.9 kg CO₂e return
  10. Glasgow, United Kingdom4.5 °C cooler · 7.2 h sun a day · 3.4 mm rain a dayrail ≈ 10h 18m · 54.8 kg CO₂e return

Without flying

The coolest places the train reaches within 15 hours. Dundee is 5.1 °C cooler for 56.9 kg — about 10× less carbon than flying to Reykjavik.

  1. Dundee, United Kingdom5.1 °C cooler · 7.7 h sun a day · 2.0 mm rain a day · sea 13.9 °Crail ≈ 11h 36m · 56.9 kg CO₂e return
  2. Inverness, United Kingdom5.0 °C cooler · 7.3 h sun a day · 2.9 mm rain a dayrail ≈ 13h 24m · 67.6 kg CO₂e return
  3. Aberdeen, United Kingdom4.7 °C cooler · 8.4 h sun a day · 1.6 mm rain a day · sea 13.4 °Crail ≈ 12h 48m · 61.6 kg CO₂e return
  4. Glasgow, United Kingdom4.5 °C cooler · 7.2 h sun a day · 3.4 mm rain a dayrail ≈ 10h 18m · 54.8 kg CO₂e return
  5. La Chaux-de-Fonds, Switzerland3.4 °C cooler · 9.2 h sun a day · 3.5 mm rain a dayrail ≈ 6h 12m · 11.4 kg CO₂e return
  6. Memmingen, Germany2.5 °C cooler · 9.6 h sun a day · 3.5 mm rain a dayrail ≈ 6h 54m · 17.3 kg CO₂e return

≈ is the model's estimate (air times include getting to and through the airport); ✓ is a rail journey checked against a real timetable, with the date it was checked. Temperatures are historical daily means for 2023–2024, averaged across day and night, so afternoons run warmer.

The low-carbon trade-off

The coolest place you can reach from Paris in September within 15 hours is Reykjavik, 10.0 °C cooler, costing 561 kg CO₂e return. The lowest-carbon option is La Chaux-de-Fonds at 11.4 kg — 49× less carbon, for 6.6 degrees less relief from the heat.

Every destination here is on the efficiency frontier: nowhere else this site covers is both cooler in September and lower in carbon. Anything a better option beats outright has been left out.

La Chaux-de-FondsReykjavik
Where they are. Solid lines are rail or ferry, dashed are flights, from Paris. Pick one to compare.
Carbon against relief from the heat, September, departing Paris. Journeys of up to 15 hours each way.6 destinations. Lowest carbon La Chaux-de-Fonds at 11.4 kilograms and 3.4 °C cooler; best for relief from the heat Reykjavik at 561 kilograms and 10.0 °C cooler. La Chaux-de-Fonds · 11.4 kgStirling · 56.0 kgKristiansund · 407 kgReykjavik · 561 kg

By rail or ferry By air

Carbon against relief from the heat, September, departing Paris. Journeys of up to 15 hours each way.
September from Paris — 6 destinations on the frontier, 3 without flying.
DestinationHowCO₂e returnTempSun/dayRain/dayJourney
La Chaux-de-Fonds, SwitzerlandRail11.4 kg14.1 °C9.2 h3.5 mm6h 12m
Buxton, United KingdomRail28.6 kg12.8 °C7.1 h3.9 mm8h 36m
Stirling, United KingdomRail56.0 kg12.3 °C7.2 h3.3 mm11h 24m
Kristiansund, NorwayAir407 kg11.6 °C7.1 h6.5 mm5h 42m
Östersund, SwedenAir443 kg10.7 °C7.7 h2.6 mm5h 48m
Reykjavik, IcelandAir561 kg7.5 °C6.3 h3.5 mm6h 30m

Warm is not the same as pleasant, which is why sunshine and rainfall are shown alongside temperature. All three are ERA5 monthly means for 2023–2024.

Where the curve breaks

The frontier is gentle until it isn't. Going from Stirling (56.0 kg, 5.2 °C cooler) to Kristiansund (407 kg, 5.9 °C cooler) buys 0.7 °C more relief from the heat for an extra 351 kg — 502 kg of CO₂e per degree. That single step is the most expensive relief from the heat on the whole curve.

The pick of them

La Chaux-de-FondsSwitzerland11.4 kg CO₂e return14.1 °C · 9.2 h sun · 6h 12m by railmild and brightStirling, United KingdomStirlingUnited Kingdom56.0 kg CO₂e return12.3 °C · 7.2 h sun · 11h 24m by railmild and brightReykjavik, IcelandReykjavikIceland561 kg CO₂e return7.5 °C · 6.3 h sun · 6h 30m by aircool

The same month, asked differently

September answers differently depending on what you are after, and the lists genuinely diverge: the brightest places are not the hottest, and in summer the useful question stops being where is warm at all.

Where to stay in Reykjavik

Places to stay in Reykjavik, Iceland, on a live map. Prices and availability come from Stay22 and its booking partners.

Search places to stay in Reykjavik →Opens the booking search in a new tab. Same partners as the map below.

Affiliate disclosure. A booking made through this map may earn 0xCarbon a commission, at no extra cost to you. It changes nothing above it: the emissions figures come from UK Government conversion factors and are computed before anyone is paid anything.See the method.

Other months from Paris

September from elsewhere

Photo credits

Questions

Where is the coolest place to go from Paris in September?

Reykjavik, Iceland, at 10.0 °C cooler. Reaching it emits 561 kg CO₂e return, travelling 6h 30m each way by air (modelled).

Can I get somewhere cool from Paris in September without flying?

Yes. Stirling reaches 5.2 °C cooler and is reachable by rail or ferry in 11h 24m (modelled), emitting 56.0 kg CO₂e return — though Reykjavik is cooler still, if you fly.

How much carbon does a return trip from Paris to Reykjavik produce?

561 kg CO₂e for one person, return, by air. That uses the UK Government's 2026 conversion factors, including radiative forcing for flights.

Carbon uses UK Government (DESNZ/DEFRA) 2026 conversion factors applied to great-circle distance, with radiative forcing included for flights. Rail journey times are modelled estimates, not timetabled services. Full method · download the data.