At 7am the Windguru forecast says 18 km/h NNW by 11:00. By noon it's 23 knots and the cliff is working beautifully. At 15:00 the briefing shows a sea-breeze front pushing 15 km inland — the XC window opens, conditions and direction changing fast. If you understand what drives all of this, you can plan the day correctly. If you don't, you're reacting to weather rather than reading it. This guide explains the large-scale patterns behind Portuguese flying — the Azores High, the Nortada, the sea breeze convergence — so you can read the forecast, not just receive it.
The Azores High — The Engine Behind Portuguese Flying
The dominant large-scale weather feature affecting Portugal is the Azores High, a semi-permanent anticyclone centred over the Atlantic Ocean southwest of the Azores archipelago. In summer, this high-pressure system expands and strengthens, pushing its circulation toward the Iberian Peninsula and setting up the northerly wind regime that drives Portugal's best flying weather.
When the Azores High is well-positioned:
- A persistent northerly flow develops along the Portuguese coast, called the Nortada
- The sky above the coast is clear or lightly clouded — the high suppresses frontal systems
- Coastal flying conditions are highly reliable for days or even weeks at a time
- Inland thermal conditions develop daily as the land heats under the clear sky
When the Azores High weakens or shifts — particularly in spring and autumn — Atlantic fronts can push through Portugal, bringing cloud, rain, and strong unstable winds. These windows typically last 2–5 days before the high reasserts itself.
The Nortada (literally "the northerly" in Portuguese) is the sustained NNW–NW surface wind that blows along Portugal's Atlantic coast from roughly May to September. It is strongest in the afternoon (typically 14:00–18:00 local) and weakest in the morning. It is the primary lift source for coastal paragliding at Sesimbra — a reliable Nortada means a reliable flying day. Learning to predict its strength and timing is the first skill in reading Portuguese weather.
The Daily Cycle — How Conditions Evolve Through the Day
On a typical Portuguese summer flying day, conditions cycle predictably:
| Time | Conditions | Best flying type |
|---|---|---|
| 07:00–10:00 | Light wind, calm coast. Inland may be slightly hazy from overnight air. Thermals not yet started. | Ground handling, gear prep |
| 10:00–12:00 | Nortada starting to build at the coast. Inland thermals beginning — weak, wide, often dry. Coastal soaring becoming possible. | Early coastal soaring, inland thermal training |
| 12:00–15:00 | Peak Nortada at the coast. Inland thermals well-developed. Best XC conditions: sea-breeze convergence line often forms ~15–25 km inland, creating strong lift along it. | Peak coastal soaring, XC flights |
| 15:00–18:00 | Coastal wind may stay strong or drop slightly. Inland thermals starting to weaken. Sea-breeze convergence line may push further inland. | Continued coastal or late XC |
| After 18:00 | Wind dropping, thermals finishing, smooth evening air. Some of the most pleasant soaring of the day, but plan landing before dark. | Evening soaring (experienced coastal pilots) |
This pattern repeats reliably on most good flying days. Understanding it lets you structure the day: ground handling in the morning calm, peak sessions at midday, debrief and rest in the late afternoon.
The Sea Breeze — A Separate Wind System
On days when the Nortada is weak, a thermal-driven sea breeze can develop independently. This is a local circulation: the land heats faster than the sea in the morning, creating a pressure differential that draws cool ocean air onshore. The sea breeze typically:
- Starts 1–2 hours after the sun heats the land (often around 10:00–11:00)
- Is onshore (westerly near Sesimbra) — different direction from the Nortada
- Strengthens through the afternoon and dies after sunset
- Can produce usable soaring conditions on days with no Nortada
The sea breeze becomes especially interesting for paragliding when it meets the southward-flowing Nortada. Where these two airflows converge, a convergence line forms — a band of rising air that can be extremely productive for XC flights. Identifying the expected position of this convergence line before a flight is one of the forecast skills I teach on XC weeks.
What Good Flying Weather Looks Like in the Forecast
For coastal soaring at Sesimbra, the ideal forecast signature:
- Surface wind: NNW–NW at 10–22 km/h at the cliff level. Under 8 km/h is marginal; over 28 km/h can be challenging for intermediate pilots.
- Wind direction: within about 30° of the cliff's aspect. If the wind goes round to the west or shifts south, the lift quality and safety margin change.
- Pressure: high pressure or ridge — no fronts approaching within 24 hours
- Cloud: light cumulus or clear above the coast is fine. Overcast low cloud (stratus from the sea) can suppress the Nortada but is usually shallow and burns off.
For XC flying (inland), the ideal additions:
- Surface heating starting by 09:00 — high sun angle, clear skies
- Cu development expected by 11:00–12:00 with cloud bases 1,500m+ AGL
- Thermal strength moderate, not overdeveloped — no risk of cumulonimbus
- Wind above 1,500m not exceeding 35 km/h (otherwise transitions become difficult)
The Best Forecast Tools for Portugal
Windguru
The standard tool for Portuguese coastal conditions. The Windguru site specifically for Sesimbra (search "Sesimbra" on Windguru) uses multiple models and has a well-calibrated historical track record for the Nortada. The WG model tends to be slightly more accurate locally than GFS for surface wind speed. Check the 850 hPa level (roughly 1,500m) for the synoptic wind driving the day, and the surface level for the local amplification.
Meteo Parapente
The best free paragliding-specific forecast tool. Meteo Parapente runs a dedicated model optimised for paragliding conditions — thermal strength, cloud base height, boundary layer depth, thermic index, and soaring potential are all displayed geographically. I use it for every XC day to identify where the best thermals are expected along a proposed route, and to watch the predicted position of the sea-breeze convergence zone.
SkySight
The best paid XC-specific tool for serious cross-country planning. SkySight's rasp and thermal forecast layers are more refined than any free alternative. If you're flying XC seriously and planning routes over 60–80 km, the SkySight subscription is worth the cost — the detail on thermal timing, cloud development, and wind at multiple levels makes a material difference to route planning.
Meteoblue and ICON model
Meteoblue with the ICON model runs at 1 km resolution over Europe. Good for identifying local effects around specific topography — for example, how the Serra da Arrábida channels or blocks wind on a given direction. I use it alongside Windguru for days where the synoptic pattern seems ambiguous.
Windy (Ventusky)
Excellent visualisation of wind fields at multiple levels. I use it to check the 850 hPa flow direction (synoptic) versus the surface forecast, and to watch for wind shear layers that could indicate turbulent transitions at altitude on XC days.
Sat24 and Skippy Sky
Live satellite imagery for watching actual cloud development versus the forecast. Satellite shows you what's happening now; the forecast shows what should happen in 6 hours. When they disagree, look at what the satellite is doing — it's more recent data.
What I Do the Night Before a Flying Day
My standard pre-flying forecast check:
- Check Windguru for Sesimbra — surface wind speed and direction for the next 12 hours. This determines whether coastal flying is on and which aspect will work best.
- Check Meteoblue ICON for the 850 hPa level — confirms the synoptic driver matches the surface forecast. If they disagree significantly, the forecast is uncertain.
- Check Meteo Parapente for thermal development (XC days only) — expected cloud base, thermic index, and convergence position. Cross-reference with SkySight on days where the XC route is longer or conditions look complex.
- Check Windy 500 hPa level — looking for any troughs or instability approaching from the Atlantic that might develop during the day.
- Check live satellite at 07:00 on the morning of flying — confirming or updating the overnight forecast before briefing the group.
Weather briefings at Fly with Behrooz happen every morning before we decide the day's programme. You don't need to do this analysis yourself — but understanding the reasoning behind the calls I make is part of what you'll learn on any week with me.
Frequently Asked Questions
How many flyable days should I expect in a week?
During the main Nortada season (May–September), most weeks have 5–6 flyable days. Weeks with fewer than 4 flyable days are rare in peak season. Spring (April) and autumn (October) have slightly more variability — expect 4–5 flyable days per week on average. Winter months have more frontal activity, reducing reliability to 3–4 days per week at best. You only pay for days you fly, so a slower week has a natural financial adjustment built in.
What happens to conditions during a heatwave?
During intense summer heat (typically affecting Portugal in July and early August), the thermal contrast between land and sea increases dramatically — this actually tends to strengthen the Nortada and produce excellent coastal soaring. The risk is that inland conditions can become overdeveloped in the afternoon (strong, rough thermals, risk of CBs). We typically keep to coastal flying during heat extremes and avoid inland XC in the 13:00–16:00 peak heating window.
Can I learn to do my own forecast analysis from this?
Yes — and I actively encourage it. Part of the daily briefing at Fly with Behrooz is explaining the reasoning behind the forecast reading, not just telling you the outcome. By the end of a week, most pilots have a working understanding of why we flew on certain days and not others, and how to read Windguru and XCSkies for Portuguese conditions. This is a transferable skill — the same approach works for reading conditions at any Atlantic-facing site.
Fly when the Atlantic is in your favour
I send a weather brief to every pilot in the group each morning — and I explain the reasoning behind every decision. Weather understanding is part of what you take home from a week in Portugal.