Ocean forecast: Umtentweni and Melkbosstrand

Choose a place from the menu at the top of the forecast, then pick an activity.

A free, five-day coastal forecast for Umtentweni on the KZN South Coast and Melkbosstrand on the West Coast. It splits each day into six four-hour windows and gives each window a Conditions score from 0 to 100 for one of four activities: fishing, surfing, kitesurfing or launching a boat.

It is a rule-based index from 0 to 100 that compares forecast windows for one activity at one place, so you can see which window looks better than another. It is not a probability, not a prediction of a catch or a good session, and not a safety rating.

The score combines the forecast with how the beach faces and with what each activity prefers. Fishing, for example, weighs tide movement, swell, wind and pressure differently from kitesurfing, which cares most about steady wind from a usable direction. Higher means the forecast lines up better with what that activity usually wants.

Each column is a four-hour window and each row (a lane) is one ingredient: tide, swell, wind, pressure and sea temperature. Colours always come with a number or an icon beside them, and arrows show the direction the wind and swell come from.

• Score row: the 0 to 100 Conditions score for the activity you picked.
• Why panel: tap a window to see how each ingredient added to or took away from its score.
• Tune: sliders let you change how much each ingredient counts for you. Your settings stay on your own device, and safety warnings do not change when you tune.
• Local normal: where available, a band shows what is typical for that place and month, so you can see when conditions are unusual.
• Day row: each day shows its best window, the moon phase, springs or neaps, and sunrise and sunset.
• Updated time: the footer says when the forecast was fetched. If it gets old, a notice says so, and very old scores and warnings are hidden.

Two places today. Umtentweni, just north of the Umzimkulu River mouth near Port Shepstone, where the beach faces east-south-east. Melkbosstrand, north of Cape Town on the West Coast, where the beach faces west. The direction a beach faces matters: it decides whether a wind is onshore, offshore or cross-shore. Melkbosstrand is marked Estimated because its beach direction and sea point have not been confirmed locally yet.

The weather and marine forecasts come from Open-Meteo (CC BY 4.0), which combines several national weather models. The tide line is modelled from sea level, not read from a tide gauge or an official tide table, so turning points can be out by up to an hour. It is marked “not for navigation” for that reason.

Warnings are kept apart from the score. A window can score well and still carry a warning, for example for large waves, strong gusts or thunder, and a warning never lowers or hides the score. The warning thresholds are drafts under review. No warning does not mean it is safe: always check conditions on the day, and follow lifeguards, the NSRI and official weather warnings from the South African Weather Service.

At Umtentweni, heavy rain upstream can change the Umzimkulu river mouth (flow, debris and water quality). The forecast does not monitor the river yet.

• Five-day forecast in four-hour windows for fishing, surf, kite and boat launch
• Lanes for tide, swell, wind, pressure and sea temperature, with direction arrows
• Conditions score with a “why” breakdown for every window
• Best window, moon phase, springs or neaps, and sunrise and sunset for each day (springs tides count in the fishing score)
• Forecast age shown, with stale and expired notices; scores and warnings are hidden when the forecast is too old
• Safety warnings shown separately from the score
• Tune sliders that stay on your device
• A place menu with Umtentweni and Melkbosstrand
• Works offline from the last forecast it loaded, and is usable by keyboard and screen reader

• Confirmed local profiles: a local check of Melkbosstrand’s beach direction and sea point, so it can move from Estimated to Locally confirmed.
• Verified tides: a 30-day comparison of the modelled tide against official tide tables before any stronger claim about tide times, then verified tide-table data where it is available.
• More best-window labels: Now and Next, Best daylight window and Best in the five-day forecast, with ties shown as Joint best conditions.
• Signed-off safety rules: the draft thresholds reviewed in a pilot before they are called stable; a long-period swell warning tested quietly first.
• River mouth: a validated river flow or level source for the Umzimkulu mouth, before any river warning is shown.
• Better scoring: tide-aware surf for a named break, and local normals feeding the score, not only the display.
• Feedback: a simple way to say a score seemed too high or too low, or that a warning seemed missing, to tune the model.
• More places: further KZN South Coast and West Coast locations as their profiles are checked.

Emilio Martin of FactSmith built it for the local fishing, surf and boating community, and as the public sample of the FactSmith conditions forecast that coastal businesses can embed on their own websites. This page is free to use and carries no advertising. For your own website, it is an add-on to every FactSmith Sites package: see the Conditions forecast page for what it costs and why.

On client websites the forecast data runs on a commercial subscription with our data provider, which FactSmith arranges and manages and which is included in the monthly fee.