EuroVelo 1 - Atlantic Coast Route - part France, stage 4: Nantes → Pornic

On stage 4 (Nantes → Pornic, 108 km) the best month is September: 82% of days were dry with highs of 10–30 °C; the wind barely favours either direction (1.3 km/h on average; ERA5 2006–2025, 9:00–18:00).

ERA5 2006–2025 · OpenStreetMap · Methodology and sources

← EuroVelo 1 - Atlantic Coast Route - part France (Whole route)

108 kmLength

August–September (peak September)Best months

eitherBetter direction in the best month

1.3 km/hAverage tailwind in the best month

82%Dry days with 10–30 °C

August · 79%Best summer month

Start: Nantes · Finish: Pornic · Route geometry: OpenStreetMap / Waymarked Trails

Weather by month

Good days

Month	Good days	Rain days ≥ 1 mm	Rain, mm	Avg high	Days ≥ 30 °C	Days < 10 °C	Daylight, h
January	31%	22%	73	9 °C	0%	54%	8.9 †
February	45%	20%	58	10 °C	0%	41%	10.2 †
March	62%	24%	60	12 °C	0%	19%	11.8
April	79%	19%	50	16 °C	0%	3%	13.5
May	78%	22%	55	18 °C	0%	0%	15.1
June	78%	19%	51	22 °C	3%	0%	15.9
July	78%	16%	45	23 °C	7%	0%	15.6
August	79%	15%	43	23 °C	6%	0%	14.2
September	82%	16%	44	21 °C	2%	0%	12.5
October	77%	22%	76	17 °C	0%	1%	10.8 †
November	62%	25%	81	13 °C	0%	15%	9.2 †
December	37%	26%	81	10 °C	0%	42%	8.5 †

Best months are all months within 3 percentage points of the best one. † less than 11 hours of daylight — long stages get tight.

Wind by month

Wind Nantes → Pornic, km/h

Month	Wind Nantes → Pornic, km/h	Headwind > 15 km/h, Nantes → Pornic	Headwind > 15 km/h, Pornic → Nantes	Better way
January	−3.0	20%	8%	Pornic → Nantes
February	−2.5	20%	11%	Pornic → Nantes
March	−1.5	19%	12%	either
April	−0.4	14%	11%	either
May	−1.8	17%	10%	either
June	−2.2	15%	7%	Pornic → Nantes
July	−4.3	21%	6%	Pornic → Nantes
August	−3.7	17%	6%	Pornic → Nantes
September	−1.3	14%	8%	either
October	−2.1	16%	8%	Pornic → Nantes
November	−2.9	19%	8%	Pornic → Nantes
December	−3.3	21%	10%	Pornic → Nantes

Along the route (sections of about 25 km)

km	Heading	Tailwind in September, km/h
376–401	W	−2.1
401–426	NW	−3.5
426–451	SW	−2.7
451–476	S	+1.3
476–484	E	+4.2

Other stages

How to read the numbers

Wind is the 10 m wind of a 25-km grid cell, daytime hours 9:00–18:00 local solar time; at saddle height in a sheltered valley it is weaker, on a coast or ridge stronger. A positive value is a tailwind. ERA5 slightly over-counts days with ≥ 1 mm of rain (by about 5–7 percentage points) and underestimates daily highs by 1–2 °C. Good day = less than 1 mm of rain between 9:00 and 18:00 (riding hours, local solar time) and a high between 10 and 30 °C; rain at night or in the evening does not spoil it.