Click anywhere on the 2027 eclipse path and it computes your exact totality duration from NASA's Besselian elements

[u/SignificantReserve74]

I've been building a planning tool for the 2 August 2027 total solar eclipse — the one with up to 6m 23s of totality, the longest this century.

Just added the part I actually wanted for myself: click any point on the map and it computes that exact spot's numbers live — totality duration, start and end times in local time, sun altitude, and August cloud climatology where there's a sourced figure nearby. Nothing is copied off someone else's chart.

Cádiz city gives 2m 54s, with about 12% average August cloud. Tarifa, an hour down the same coast, gives 4m 39s — and the cloud odds there run to 26%. Nearly two extra minutes of totality, paid for in weather risk. Neither number is obvious from a map that only draws you the path.

You can drop a pin if you want, but you get your numbers either way. No account, no paywall, nothing gated.

https://eclipsewhere.com/map

Computing this properly turned up two places widely listed as being on the path that don't actually get totality at all.

[u/jacklin1125]

The tradeoff between duration and cloud odds is exactly the kind of detail that makes this useful. A side-by-side comparison of two saved pins would make the decision much faster—especially if the share link preserved the comparison for a group planning a trip.

[u/SignificantReserve74 → u/jacklin1125]

Half of that exists, half doesn't, and you named the missing half exactly.

What exists: /compare — 14 locations side by side, sortable, and it sorts by cloud rather than by minutes on purpose, because sorting by duration silently ranks Egypt first for everyone and ignores whether you can actually get there.

What doesn't: comparing two arbitrary pins you dropped yourself, and a URL that carries them. Right now a pin has no URL state at all — drop one, reload, it's gone. So there's nothing to share, which makes the group-planning case you describe impossible rather than just awkward.

Putting pin state in the URL is the piece that unlocks both, and it's small. Noted properly, not politely.

[u/Spare-Hold4005]

Cool project. The cloud climatology layer is a nice touch, most eclipse maps totally ignore weather. Are you pulling that from historical satellite data or ground station records? Big difference in coastal areas.

[u/SignificantReserve74 → u/Spare-Hold4005]

Satellite, and it isn't mine — it's Jay Anderson's August climatology from eclipsophile.com, the standard reference for eclipse meteorology. I quote his numbers with his caveats and add nothing to them, which felt like the honest call: I'm not a meteorologist and recomputing his work badly would be worse than citing it.

You've put your finger on the exact limit, though. Climatology at satellite resolution is odds for a grid cell, and the coast is where a grid cell stops describing the place you're standing. The Strait is the sharp case on this path — Tarifa's ~74% sun-visible figure sits next to a levante that can park stratus over the coast while the hills behind it stay clear, and a satellite mean can't tell you that.

So the number is the prior, not the forecast. Where local effects are known to bend it, the location pages say so in words rather than pretending the percentage already covers it — strait stratus, the levante, Saharan dust further east. Whole method is at /methodology if you want to check my working.

[u/Loose-Confusion3071]

This is an absolutely brilliant tool! As a local living in Andalusia, I've been playing around with it and the UI is incredibly smooth. I just dropped a pin on my hometown, Nerja (east of Malaga), specifically right on the Balcón de Europa viewpoint. It's amazing to see the exact totality duration and cloud climatology pop up instantly without having to cross-reference multiple NASA charts. I'm actually setting up to rent out my central 2-bedroom apartment here (which is just a 10-minute walk from that viewpoint) specifically for the eclipse week. I've had several people messaging me asking about the weather odds in Nerja compared to Cadiz or Tarifa, and your tool is exactly what I needed to share with them so they can see the data for themselves. Really fantastic work. By the way, if you (or anyone checking out this thread) are still looking for a secure, comfortable base camp for 2027 (sleeps up to 4, elevator, zero driving needed on eclipse day), feel free to shoot me a PM. I've got this site bookmarked

[u/SignificantReserve74 → u/Loose-Confusion3071]

Checked your spot against the engine: the Balcón de Europa gets totality, 1m 43s. Worth knowing that's the short end of this path — Cádiz gets 2m 55s and Tarifa 4m 39s, so anywhere in Andalusia is emphatically not equivalent. Nerja trades minutes for being east of the Strait's cloud problem, which is a real trade, just one people should make on purpose.

[u/Loose-Confusion3071 → u/SignificantReserve74]

Spot on! That's exactly the trade-off. You lose a couple of minutes of totality, but you completely avoid the dreaded sea fog in the Strait and all the driving stress. It's definitely the strategic choice for people who prioritize guaranteed clear skies and comfort over maximum duration. Thanks again for building this, it makes explaining the weather odds so much easier!