Montevideo is overcast and raw today, 14°C/57°F now but feeling more like 11°C/52°F, with a high of just 15°C/59°F and an overnight low of 7°C/45°F expected. Light drizzle (about 1 mm) and wind near 20-23 km/h (12-14 mph) round out a classic late-August gray day; humidity sits at 74%. Punta del Este is a touch milder, topping out near 17°C/63°F, but under the same thick cloud cover.

That calm won't last. Uruguayan meteorologists agree the so-called temporal de Santa Rosa — the cold front tied to the Aug. 30 feast day of Santa Rosa de Lima that reliably rattles the Río de la Plata region each spring — will begin moving into Uruguay on Thursday, Aug. 27. Forecaster José Serra told local press the worst hours will fall between Thursday and Friday, Aug. 28, with the heaviest impact expected in Rivera, Cerro Largo, Rocha and Artigas, while the south sees lighter effects. Rainfall totals of 10 to 30 millimeters are expected, with some heavy bursts, plus strong wind and a chance of hail. Our own forecast data show the coast getting the worst of it: Punta del Este's rain total jumps from barely 1.5 mm today to 28.5 mm on Thursday under a thunderstorm label, before conditions turn merely overcast and cool again into the weekend (11-13°C/52-55°F highs through Monday).

What it means: pack a rain shell and expect possible delays to buses, ferries and flights Thursday into Friday, especially near the coast or up north in Rivera or Rocha. After the front passes, plain gray cold settles back in — no more storms are on the six-day board.

Inumet is the national service and it is the reference for official warnings, which is why every alert on this site is sourced to it. But it is not always the fastest to see weather arriving from the north, and Uruguay’s worst days usually arrive from Brazil.

On Aug. 9 this year MetSul was five days ahead of Inumet on the flooding that followed. That is not a criticism of a meteorologist; it is a structural fact about where the models are run and which country’s territory a service is watching. So our forecast is a consensus of the major global models rather than any single office, we source every official warning to Inumet, and we watch the Brazilian and Argentine services for weather approaching from upwind.

Reading the models together is more reliable than trusting any one office. The Brazilian services see cold and storm systems while those are still over Rio Grande do Sul, often a day or more before they reach the Río de la Plata; the Argentine services pick up fronts approaching from upwind; and Inumet is the authority once the weather is over Uruguay. When the models agree, the forecast is solid and that is what we publish, in Celsius and Fahrenheit. When they split on the days ahead, the disagreement is the story, and we say which way we lean and why.

No official Inumet warning and no frost or storm signal in the forecast window. Official warnings, when issued, come from Inumet.

Inumet publishes no sensación térmica value. The feels-like figures here are computed by the standard wind-chill formula from the published temperature and wind. They are ours, not a forecast, and we label them wherever they appear.