Warsaw · September · relief from the heat

Coolest places to go from Warsaw in September

In September, the coolest well-known place within 15 hours of Warsaw is Reykjavik, Iceland, 10.8 °C cooler than Warsaw and 6.3 h sun a day, about 7h 12m each way by air. Without flying, it is Västerås, Sweden, 4.6 °C cooler than Warsaw, about 14h 12m each way by train, for about 27× less carbon (25.6 kg CO₂e return against 697 kg).

The 10 coolest places within 15 hours of Warsaw

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, Iceland10.8 °C cooler · 6.3 h sun a day · 3.5 mm rain a day · sea 10.8 °Cair ≈ 7h 12m · 697 kg CO₂e return
Tromsø, Norway8.6 °C cooler · 4.9 h sun a day · 5.2 mm rain a dayair ≈ 6h 6m · 488 kg CO₂e return
Östersund, Sweden7.6 °C cooler · 7.7 h sun a day · 2.6 mm rain a dayair ≈ 5h 12m · 320 kg CO₂e return
Bodø, Norway7.4 °C cooler · 5.2 h sun a day · 6.6 mm rain a day · sea 13.0 °Cair ≈ 5h 48m · 431 kg CO₂e return
Rovaniemi, Finland7.1 °C cooler · 6.0 h sun a day · 3.5 mm rain a dayair ≈ 5h 36m · 404 kg CO₂e return
Trondheim, Norway6.5 °C cooler · 7.0 h sun a day · 5.8 mm rain a dayair ≈ 5h 24m · 350 kg CO₂e return
Sundsvall, Sweden6.0 °C cooler · 8.4 h sun a day · 2.3 mm rain a day · sea 14.2 °Cair ≈ 5h · 290 kg CO₂e return
Luleå, Sweden6.0 °C cooler · 7.7 h sun a day · 2.4 mm rain a day · sea 14.3 °Cair ≈ 5h 30m · 374 kg CO₂e return
Dundee, United Kingdom5.9 °C cooler · 7.7 h sun a day · 2.0 mm rain a day · sea 13.9 °Cair ≈ 5h 42m · 406 kg CO₂e return
Glasgow, United Kingdom5.3 °C cooler · 7.2 h sun a day · 3.4 mm rain a dayair ≈ 5h 48m · 425 kg CO₂e return

Without flying

The coolest places the train reaches within 15 hours. Västerås is 4.6 °C cooler for 25.6 kg — about 27× less carbon than flying to Reykjavik.

Västerås, Sweden4.6 °C cooler · 8.2 h sun a day · 3.1 mm rain a dayrail ≈ 14h 12m · 25.6 kg CO₂e return
Uppsala, Sweden4.4 °C cooler · 8.0 h sun a day · 2.1 mm rain a dayrail ≈ 14h 30m · 25.8 kg CO₂e return
Örebro, Sweden4.2 °C cooler · 8.1 h sun a day · 2.2 mm rain a dayrail ≈ 14h · 25.5 kg CO₂e return
Zakopane, Poland3.8 °C cooler · 8.8 h sun a day · 3.9 mm rain a dayrail ≈ 5h 42m · 9.9 kg CO₂e return
Stockholm, Sweden3.7 °C cooler · 8.2 h sun a day · 1.9 mm rain a dayrail ≈ 13h 36m · 23.9 kg CO₂e return
Memmingen, Germany3.3 °C cooler · 9.6 h sun a day · 3.5 mm rain a dayrail ≈ 14h 54m · 26.7 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 Warsaw in September within 15 hours is Reykjavik, 10.8 °C cooler, costing 697 kg CO₂e return. The lowest-carbon option is Nowy Targ at 9.3 kg — 75× less carbon, for 8.0 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 Warsaw. Pick one to compare.

By rail or ferry By air

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

What the 15-hour limit costs: at this budget Lillehammer can only be reached by air — 296 kg CO₂e, in 5h 6m. Allow up to 24 hours and the train does the same journey for 34.7 kg in 18h 30m — 9× less carbon for 13h 24m more travelling.

September from Warsaw — 7 destinations on the frontier, 3 without flying.
Destination	How	CO₂e return	Temp	Sun/day	Rain/day	Journey
Nowy Targ, Poland	Rail	9.3 kg	15.5 °C	8.9 h	2.9 mm	5h 24m
Zakopane, Poland	Rail	9.9 kg	14.5 °C	8.8 h	3.9 mm	5h 42m
Västerås, Sweden	Rail	25.6 kg	13.7 °C	8.2 h	3.1 mm	14h 12m
Lillehammer, Norway	Air	296 kg	12.0 °C	7.0 h	4.6 mm	5h 6m
Östersund, Sweden	Air	320 kg	10.7 °C	7.7 h	2.6 mm	5h 12m
Tromsø, Norway	Air	488 kg	9.7 °C	4.9 h	5.2 mm	6h 6m
Reykjavik, Iceland	Air	697 kg	7.5 °C	6.3 h	3.5 mm	7h 12m

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 Östersund (320 kg, 7.6 °C cooler) to Tromsø (488 kg, 8.6 °C cooler) buys 1.0 °C more relief from the heat for an extra 168 kg — 168 kg of CO₂e per degree. That single step is the most expensive relief from the heat on the whole curve.

The pick of them

Nowy TargPoland9.3 kg CO₂e return15.5 °C · 8.9 h sun · 5h 24m by railwarm overall

VästeråsSweden25.6 kg CO₂e return13.7 °C · 8.2 h sun · 14h 12m by railmild and bright

ReykjavikIceland697 kg CO₂e return7.5 °C · 6.3 h sun · 7h 12m 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 Warsaw

September from elsewhere

Photo credits

Nowy Targ: Blooo, CC BY-SA 3.0, via Wikimedia Commons
Västerås: Einarspetz, CC BY-SA 4.0, 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
Örebro: Liberaler Humanist (image 1), Arild Vågen (image 2, 3, 4 & 5), CC BY-SA 3.0, via Wikimedia Commons
Zakopane: Maksym Kozlenko, CC BY-SA 4.0, via Wikimedia Commons
Stockholm: JZ, CC BY-SA 3.0, via Wikimedia Commons

Questions

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

Reykjavik, Iceland, at 10.8 °C cooler. Reaching it emits 697 kg CO₂e return, travelling 7h 12m each way by air (modelled).

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

Yes. Västerås reaches 4.6 °C cooler and is reachable by rail or ferry in 14h 12m (modelled), emitting 25.6 kg CO₂e return — though Reykjavik is cooler still, if you fly.

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

697 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.