Lavrion: a departure-source desk, not a generic city forecast.
Forecast sectors and coverage
Choose whether the track continues toward Kea/Cyclades or into adjacent mainland waters. The named HNMS sectors must be checked against that direction; Lavrion is a start location, not a forecast-zone definition.
Weather-sensitive legs
Treat berth, cape/gap and island arrival separately. A sheltered marina reading cannot validate the exposed leg; check wind/wave angle and the arrival coast at the ETA.
Observations, sea state and reassessment
Confirm the exact berth/entrance and an observation representative of the exposed leg, if available. Inspect timestamp, sensor status and forecast issue separately. Missing observations or local approach/current information remain explicit gaps; this page does not certify depth, navigability or port permission.
Worked planning scenario — not a live forecast
Compare two departure times at the harbour exit, first exposed leg and arrival ETA. Record the next official check and a verified alternative before the point of commitment. If the later option is better only at the berth, it has not yet improved the passage as a whole.
Official products by task
- HNMS marine bulletin — Locate the named Greek sea sectors; check the actual issue, not a city forecast.
- HNMS sea-area warnings — Marine warning entry point; distinguish sea warnings from land alerts.
- HCMR POSEIDON monitoring tools — Find observing platforms and distinguish measurements from model fields; check gaps and timestamps.
Sector names help you locate the issuing product; they are not an automatic route-coverage match. Open the current issue and check boundaries, issue time and validity. This page does not display current warnings; an unavailable product does not mean no hazard.
Waters and sailing options
- Cyclades
Turn a Cyclades island list into a sequence of exposed gaps and workable arrival options.
- Aegean Sea
Plan the exposed island leg, not just a comfortable departure harbour.
- Saronic Gulf
Plan Athens/Piraeus–Aegina–Poros legs separately from open-Cyclades crossings.
Countries & territories
- Greece
Ionian coast, Saronic Gulf and open Aegean island passages require different plans.
Map orientation
The approximate map centre is not an approach waypoint, track, depth survey or forecast-zone boundary. The third-party map loads only on request.
Build your passage brief
Bring your route, leg timings, vessel and crew profile, checked sources and reassessment triggers into the brief. Personal AI analysis and expert review are available to invited closed-test participants; a port page does not extend the calculation service’s coverage.
A Sailing Weather editorial guide to local conditions, practical passage preparation and marine-weather sources. Source and structure review: 27 September 2026. For a specific passage, check current issues, validity and forecast coverage. The skipper retains the final decision and responsibility.
Lavrion is not a generic Athens departure
Use the actual marina and exit in the route inputs. A Lavrion–Kea/Cyclades departure and a Piraeus-area Saronic day have different headings, first exposed legs and candidate marine sectors. Do not label the same coordinate Athens and reuse its forecast for both. Confirm the sector from the plotted first leg, retaining official names and validity, before comparing departure hours.
- HNMS marine sectors — Named Greek sea sectors; not automatic route matching Direct product verification is limited; obtain the current issue from the issuer.
Use charter handover time as a constraint
An afternoon handover can delay reaching the first exposed gap. Compare a shorter first leg with the planned longer island arrival at the revised ETA, rather than assuming a morning forecast describes the whole first day. Identify the next current-source check before leaving shelter and obtain harbour information independently. This departure desk is a starting point for a passage brief, not confirmation of a berth or a pre-cleared island refuge.
- HNMS marine bulletin guide — Units, time terms, warning structure Direct product verification is limited; obtain the current issue from the issuer.
Editorial review of this material: 27 September 2026. This date concerns the page content; check current forecast issue times and validity at the original sources.