How to read a Nation Watch SA forecast page
What each number on our city forecast pages means, where it comes from and how far to trust it.
By Staff Reporter · Published
Every morning, and every three hours during the day, we update a forecast page for each place we cover. Here is what you will find on it.
Where the numbers come from
Our forecasts come from MET Norway, the Norwegian Meteorological Institute, which publishes global forecast data under an open licence. Outside Scandinavia its forecasts are based on the global model run by the European Centre for Medium-Range Weather Forecasts (ECMWF). We take that data, work out the daily highs, lows and rainfall for South African time, and present it in plain English.
These pages are produced automatically. They are not official forecasts and they are never warnings. Official severe-weather warnings in South Africa come only from the South African Weather Service (SAWS); see our warnings hub and how our forecast pages work.
The sections on each page
- Headline and summary: today’s high and conditions, and a one-line summary.
- Tomorrow: a separate section with tomorrow’s high, low, rain and wind.
- Current conditions: the model’s estimate for the current hour, not a reading from a weather station. It can differ from what you see outside.
- Next 24 hours: temperature, conditions and expected rainfall for each hour.
- 7-day forecast: the high and low for each day, the main conditions around midday, total rainfall and the strongest sustained wind.
- UV index: the clear-sky maximum for the day. Cloud lowers it, but on clear days the South African sun is strong.
- Wind: sustained wind speed. Gusts can be considerably stronger, especially in thunderstorms.
How far ahead to trust it
Forecasts are most reliable for today and tomorrow. Beyond three or four days, treat them as a guide to the general pattern rather than a promise, and check again closer to the time.
When the page carries a warning box
If SAWS has issued a warning for the province in the last 36 hours, the forecast page shows a box linking to the details. Always check SAWS for the warning level, the period it covers and the areas affected.
How we make our journalism: every article is checked, edited and approved by our Editor-in-Chief before publication, and SAWS is credited for every warning we report. See our editorial policy.
Spotted an error? Read our corrections policy.