Brussels · September · relief from the heat

Coolest places to go from Brussels in September

In September, the coolest well-known place within 15 hours of Brussels is Reykjavik, Iceland, 9.6 °C cooler than Brussels and 6.3 h sun a day, about 6h 18m each way by air. Without flying, it is Dundee, United Kingdom, 4.7 °C cooler than Brussels, about 11h 18m each way by train, for about 9× less carbon (56.3 kg CO₂e return against 535 kg).

The 10 coolest places within 15 hours of Brussels

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.

Reykjavik, Iceland9.6 °C cooler · 6.3 h sun a day · 3.5 mm rain a day · sea 10.8 °Cair ≈ 6h 18m · 535 kg CO₂e return
Tromsø, Norway7.4 °C cooler · 4.9 h sun a day · 5.2 mm rain a dayair ≈ 6h 30m · 560 kg CO₂e return
Östersund, Sweden6.4 °C cooler · 7.7 h sun a day · 2.6 mm rain a dayair ≈ 5h 30m · 378 kg CO₂e return
Bodø, Norway6.2 °C cooler · 5.2 h sun a day · 6.6 mm rain a day · sea 13.0 °Cair ≈ 6h · 480 kg CO₂e return
Rovaniemi, Finland5.9 °C cooler · 6.0 h sun a day · 3.5 mm rain a dayair ≈ 6h 18m · 531 kg CO₂e return
Trondheim, Norway5.3 °C cooler · 7.0 h sun a day · 5.8 mm rain a dayair ≈ 5h 24m · 363 kg CO₂e return
Sundsvall, Sweden4.8 °C cooler · 8.4 h sun a day · 2.3 mm rain a day · sea 14.2 °Cair ≈ 5h 30m · 378 kg CO₂e return
Luleå, Sweden4.8 °C cooler · 7.7 h sun a day · 2.4 mm rain a day · sea 14.3 °Cair ≈ 6h 6m · 485 kg CO₂e return
Dundee, United Kingdom4.7 °C cooler · 7.7 h sun a day · 2.0 mm rain a day · sea 13.9 °Crail ≈ 11h 18m · 56.3 kg CO₂e return
Glasgow, United Kingdom4.1 °C cooler · 7.2 h sun a day · 3.4 mm rain a dayrail ≈ 10h · 54.1 kg CO₂e return

Without flying

The coolest places the train reaches within 15 hours. Dundee is 4.7 °C cooler for 56.3 kg — about 9× less carbon than flying to Reykjavik.

Dundee, United Kingdom4.7 °C cooler · 7.7 h sun a day · 2.0 mm rain a day · sea 13.9 °Crail ≈ 11h 18m · 56.3 kg CO₂e return
Inverness, United Kingdom4.6 °C cooler · 7.3 h sun a day · 2.9 mm rain a dayrail ≈ 13h 6m · 66.9 kg CO₂e return
Aberdeen, United Kingdom4.3 °C cooler · 8.4 h sun a day · 1.6 mm rain a day · sea 13.4 °Crail ≈ 12h 30m · 60.9 kg CO₂e return
Glasgow, United Kingdom4.1 °C cooler · 7.2 h sun a day · 3.4 mm rain a dayrail ≈ 10h · 54.1 kg CO₂e return
La Chaux-de-Fonds, Switzerland3.0 °C cooler · 9.2 h sun a day · 3.5 mm rain a dayrail ≈ 8h 30m · 13.4 kg CO₂e return
Kristiansand, Norway2.8 °C cooler · 8.2 h sun a day · 4.7 mm rain a day · sea 16.4 °Crail ≈ 14h 12m · 24.9 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 Brussels in September within 15 hours is Reykjavik, 9.6 °C cooler, costing 535 kg CO₂e return. The lowest-carbon option is Villingen-Schwenningen at 12.7 kg — 42× less carbon, for 7.2 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.

Where they are. Solid lines are rail or ferry, dashed are flights, from Brussels. Pick one to compare.

By rail or ferry By air

Carbon against relief from the heat, September, departing Brussels. Journeys of up to 15 hours each way.

What the 15-hour limit costs: at this budget Östersund can only be reached by air — 378 kg CO₂e, in 5h 30m. Allow up to 24 hours and the train does the same journey for 44.3 kg in 23h 42m — 9× less carbon for 18h 12m more travelling.

September from Brussels — 7 destinations on the frontier, 4 without flying.
Destination	How	CO₂e return	Temp	Sun/day	Rain/day	Journey
Villingen-Schwenningen, Germany	Rail	12.7 kg	14.7 °C	9.3 h	3.0 mm	8h 12m
La Chaux-de-Fonds, Switzerland	Rail	13.4 kg	14.1 °C	9.2 h	3.5 mm	8h 30m
Buxton, United Kingdom	Rail	27.9 kg	12.8 °C	7.1 h	3.9 mm	8h 18m
Stirling, United Kingdom	Rail	55.3 kg	12.3 °C	7.2 h	3.3 mm	11h 6m
Kristiansund, Norway	Air	347 kg	11.6 °C	7.1 h	6.5 mm	5h 18m
Östersund, Sweden	Air	378 kg	10.7 °C	7.7 h	2.6 mm	5h 30m
Reykjavik, Iceland	Air	535 kg	7.5 °C	6.3 h	3.5 mm	6h 18m

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 (55.3 kg, 4.8 °C cooler) to Kristiansund (347 kg, 5.5 °C cooler) buys 0.7 °C more relief from the heat for an extra 291 kg — 416 kg of CO₂e per degree. That single step is the most expensive relief from the heat on the whole curve.

The pick of them

Villingen-SchwenningenGermany12.7 kg CO₂e return14.7 °C · 9.3 h sun · 8h 12m by railmild and bright

StirlingUnited Kingdom55.3 kg CO₂e return12.3 °C · 7.2 h sun · 11h 6m by railmild and bright

ReykjavikIceland535 kg CO₂e return7.5 °C · 6.3 h sun · 6h 18m 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 Brussels

September from elsewhere

Photo credits

Stirling: Stirling Council from Stirling, UK, CC BY 2.0, via Wikimedia Commons
Reykjavik: Hedwig Storch, CC BY-SA 3.0, via Wikimedia Commons
Tromsø: Diego Delso, CC BY-SA 4.0, via Wikimedia Commons
Östersund: Lars Falkdalen Lindahl (User:Njaelkies Lea), CC BY-SA 3.0, via Wikimedia Commons
Bodø: Røed 20:41, 24 July 2006 (UTC), CC BY-SA 2.5, via Wikimedia Commons
Trondheim: Åge Hojem/Trondheim Havn from Trondheim, Norway, CC BY-SA 2.0, via Wikimedia Commons
Sundsvall: User:Ö1thpe0807 (image 1), User:I99limpan (image2), User:Larskallin (image3), Hans Lindqvist (image 4-5), Calle Eklund (, CC BY-SA 3.0, via Wikimedia Commons
Luleå: Andreas Harnemo, CC BY-SA 3.0, via Wikimedia Commons
Dundee: File:442 dundee header.png (Tay Bridge and RSS Discovery images):- Original: PlutosAcademy File:V&A Dundee Near Completi, CC BY-SA 4.0, via Wikimedia Commons
Glasgow: 瑞丽江的河水, CC BY-SA 4.0, via Wikimedia Commons
Aberdeen: Ragazzi00, CC BY-SA 3.0, via Wikimedia Commons
Kristiansand: unknown author, CC BY 2.5, via Wikimedia Commons

Questions

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

Reykjavik, Iceland, at 9.6 °C cooler. Reaching it emits 535 kg CO₂e return, travelling 6h 18m each way by air (modelled).

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

Yes. Stirling reaches 4.8 °C cooler and is reachable by rail or ferry in 11h 6m (modelled), emitting 55.3 kg CO₂e return — though Reykjavik is cooler still, if you fly.

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

535 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.