A total eclipse with the Sun near the horizon adds a variable that high-Sun eclipses barely have to think about: the sliver of sky just above the western skyline needs to be clear, not the whole dome overhead. A cloud bank sitting low in the west can ruin an otherwise perfect eclipse even under an apparently clear sky. So the project ran the numbers on thirty years of 12 August weather — ERA5 reanalysis, 1996 to 2025, gridded at roughly 25 km per cell — to see where that gamble actually pays off.
The safest bet: the Valencia coast and Ibiza
The single best odds in the entire totality band sit on the Valencia coastline and over Ibiza: 23 of 30 years (77%) came up clear on 12 August, with average cloud cover of just 19–22%. It’s not close — nowhere else in the band gets near that number on the day itself.
The riskiest bet: interior Asturias and Lugo
At the opposite end, the mountainous interior of Asturias and Lugo — right where the shadow first crosses into Spain — has been clear on 12 August in exactly 1 of 30 years (3%), with average cloud cover of 61–69%. Of the whole band, it’s by far the riskiest place to plant a tripod.
The middle ground: the Ebro valley and the eastern plateau
Between the two extremes, Zaragoza, Teruel and Guadalajara — the eastern plateau and Ebro valley — offer a solid, unspectacular bet: 15 to 18 of 30 years clear (50–60%), average cloud cover around 26–29%. That advantage erodes fast moving north, though: Burgos, already at the edge of wet Spain, drops to 7 of 30 years clear (23%), with average cloud cover climbing to 47%.
Does shifting your dates help?
It depends enormously on where you already stand. The dataset also tracks a wider ±2-week window around 12 August, and the two extremes react in opposite ways. Over Ibiza and the Valencia coast, widening the window barely moves the needle — 76.3% clear across the window versus 76.7% on the day itself, because there’s essentially no ceiling left to gain. Over interior Asturias, the same widening roughly quadruples your odds — from 3.3% on the exact date to 12.9% across the surrounding fortnight. If you’re gambling on the wettest corner of the band, that gap says a lot about how unlucky that single date historically is compared to the season around it — even though the eclipse itself is fixed to 12 August regardless. Zaragoza and Burgos show a smaller version of the same effect: the Ebro valley’s window average (65.1%) actually beats its single-day figure (60%), while Burgos improves modestly too (27.1% vs 23.3%).
The takeaway
None of this changes where the Moon’s shadow falls — that’s fixed by orbital mechanics, not weather. But if two towns offer comparable totality duration and a comparable horizon, thirty years of the same date’s weather is a real, data-backed reason to pick the one further southeast. The map above has a “Will it be clear?” layer with this same climatology draped over the terrain, and the town search gives the exact figure for your specific point rather than the average of a 25 km cell.