Weather · Total Eclipse 12 · VIII · 2026
The clouds that will hide the eclipse are not above your head
On 12 August, at 20:29 local time, the Sun will sit roughly 4 degrees above the horizon. At that altitude, the sky forecast for your own town stops being useful: the cloud that can ruin totality for you is not overhead, it is tens of kilometres away towards the west-northwest. Spain's national weather service has issued this warning. Here is how to work out your cloud corridor and where you should actually be looking.
Almost everyone will do the same thing on eclipse day: open a weather app, look at the icon for their town and decide accordingly. For any other astronomical event that would be exactly right, because the object sits high in the sky and the clouds that block it really are above your head.
This eclipse does not work that way. Totality happens with the Sun about to set, and that changes the geometry of the problem completely.
The mistake that will ruin observations on the day
When you look at an object 4 degrees above the horizon, your line of sight does not climb: it skims almost parallel to the ground for an enormous distance before gaining any height. Any cloud that crosses that path hides the Sun, wherever it happens to be.
The consequence is counterintuitive: you can have a perfectly clear sky overhead and see absolutely nothing, because there is a cloud bank 60 kilometres away that you would never identify as a threat. And the reverse is equally true: you can have clouds above you and see totality perfectly, provided your corridor towards the west-northwest is clean.
⚠ The official warning
AEMET warns that checking whether there are clouds directly above your observation site will not be enough: the clouds that could hide the Sun may lie towards the west, even tens of kilometres away.
Four degrees change everything
Four degrees is roughly the width of three fingers held at arm's length. It is a tiny strip of sky, and the entire observation depends on it being clear.
Azimuth is the figure almost nobody gets right. In August the Sun does not set due west, and certainly not to the southwest: it sets clearly displaced towards the north. Spain's Instituto Geográfico Nacional records 285° for the municipalities of Lleida and 286° for those of Tarragona. If you check your horizon in the wrong direction, the check is worthless.
How far away a cloud has to be to hide the Sun
The calculation is elementary trigonometry. If you know the height of the cloud and the altitude of the Sun above the horizon, the distance at which that cloud intercepts your line of sight is:
The formula
distance = cloud height ÷ tangent of the Sun's altitude
With the Sun between 4° and 5°, the multiplier sits between 11 and 14. In other words: for every 1,000 metres of cloud height, roughly 11 to 14 kilometres of distance.
| Cloud type | Typical base | Hides the Sun if it sits at |
|---|---|---|
| Low Stratus, fair-weather cumulus, coastal banks | 1,000 – 2,000 m | 12 – 29 km |
| Mid-level Altocumulus, altostratus | 3,000 – 5,000 m | 34 – 72 km |
| High Cirrus, thunderstorm anvils | 6,000 – 9,000 m | 69 – 129 km |
Distances calculated for a solar altitude of between 4° and 5°, measured in a straight line towards azimuth 286°. The calculation is a flat-plane approximation; the curvature of the Earth reduces these distances slightly, by between 3 % and 6 %, which makes the values in the table conservative.
Your cloud corridor, step by step
Set a bearing of 286° from your exact spot. Use your phone's compass or PhotoPills. Not from your town: from the precise point where you will be standing.
Draw that line on a map and mark three distances along it: 25 kilometres, 70 kilometres and 120 kilometres. That narrow strip is your area of interest. Everything outside it is irrelevant to you.
Read the radar and satellite imagery inside that strip, not above your head. Satellite images from AEMET and Meteocat will serve you far better than the icon in your weather app.
Watch afternoon convection closely. If at 19:00 there are storms 100 or 120 kilometres along your corridor, what matters is not whether it will rain where you are, but whether the anvil of those storms is spreading eastwards.
Decide your plan B before the day itself. There will be a special traffic operation and mobility restrictions across the whole path of totality. Moving somewhere else at the last minute may simply not be possible.
Where each part of Catalunya has to look
Because the azimuth is virtually identical along the whole path, each area's corridor points at a specific and easily identifiable geographical sector. This is what you should be watching, depending on where you observe from:
⚠ The trade-off nobody mentions
The duration of totality increases towards the south, but the corridor of sky improves towards the west. Alcanar gets 97 seconds and looks towards the Teruel ranges; Ponent gets fewer seconds and looks towards the Ebro valley. There is no single right answer: it depends on what the models say on the 11th.
Clouds on 12 August: what the weather services are saying
With the eclipse only days away, the general picture is one of atmospheric stability, with mostly clear or lightly clouded skies across much of the territory. Meteocat expects a largely sunny day, with some low stratus forming from dusk onwards and a chance of storms mainly over the Pyrenees and Pre-Pyrenees.
The three sources of uncertainty for the path of totality, in order of relevance:
- Convection over the Teruel section of the Iberian System. It is one of the areas where cloud most frequently develops on summer afternoons, and it coincides exactly with the visual corridor of the Terres de l'Ebre.
- Low coastal cloud and cloud over the delta. Maritime humidity can form banks at dusk; they are hard to forecast and sit at very short distances.
- Convective cloud development across the eastern third of the Peninsula during the afternoon, according to AEMET's special bulletin.
What should not worry you
Saharan dust haze is not an obstacle to observation: it slightly reduces the transparency of the sky, but it can actually deepen the orange tones of the sunset. And thin, translucent high cloud, according to AEMET itself, in most cases does not prevent the eclipse from being observed.
The statistics, for context
An analysis of Meteosat satellite imagery from the last twenty-two years, taken at 20:30 on every 12 August between 2004 and 2025, puts the chances of observing the eclipse well at around 50 %. It is a coin toss. But climatology only serves to set the scene: days away from the date, the specific forecast always takes precedence over the statistics.
Where to check the official forecast
⚠ A warning about forecasts
Any forecast figure you read in these final days has a shelf life of hours. Models are updated several times a day and the signal can shift significantly between one run and the next. Always check the current day's update, and treat with suspicion any forecast published without stating when it was issued.
Unique in Catalunya · Official IGN data
Download the Eclipse Observation Map
The free PDF guide for choosing your spot: solar direction and altitude verified against official data, plus the criteria for judging whether your horizon will work. You can also check the 221 municipalities of Catalunya inside the path of totality.
- Free PDF download
- Verified solar direction and altitude
- Works offline on eclipse day
Instant download
Eclipse Archive · 12 August 2026
Your photo makes history too
Share your photos and videos of the total solar eclipse over Catalunya and become part of the historical archive. The next one will not come until 2180.
Win prizes at PortAventura, Marineland, Aqualeon, Catalunya en Miniatura and L'Aquàrium de Barcelona.
Enter the contest →Keep the memory, not just the photo
Anyone who goes to the trouble of working out their cloud corridor, choosing a spot and deciding where to stand is exactly the person who will want to keep whatever happens on the 12th. Phone photos end up lost among thousands of files. A physical object does not.
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Methodology: the altitude and azimuth of the Sun during totality come from the official tables published by Spain's Instituto Geográfico Nacional for the eclipse of 12 August 2026. The interception distances are eclipsi26.com's own calculation, applying the trigonometric relationship between cloud height and solar altitude across the 4° to 5° range, without correcting for the curvature of the Earth or atmospheric refraction, which makes them slightly conservative. The geographical sector of each corridor is eclipsi26.com's own calculation, projecting azimuth 286° from the reference coordinates of each area. The forecasts cited come from the special bulletin issued by AEMET and from the special forecast issued by the Servei Meteorològic de Catalunya, both updated daily until 12 August. The twenty-two-year statistic comes from the Meteosat imagery analysis reported by Catalan media. Eye-safety recommendations are based on the ISO 12312-2:2015 standard. This article was last updated on 8 August 2026.