An unseasonably mild start to the week is expected in northern and central parts of Argentina, where it is winter. A plume of warm air will sink southwards from neighbouring Paraguay on Monday, lingering through Tuesday, before giving way to a cold front on Wednesday.
The maximum daytime temperatures on Monday and Tuesday will be up to 5C (9F) higher than normal in these regions, while Buenos Aires is forecast to be about 7C above average on Tuesday.
Meanwhile, it is expected to be 5-8C above normal at night, with minimums in the low to mid-teens. Rosario, the largest city in the province of Santa Fe, about 186 miles (300km) to the north-west of Buenos Aires, will experience the mildest temperatures, with a minimum of 14-15C forecast on Monday, near 10C above the climate average.
Warm air could trigger heavy showers and thunderstorms across Buenos Aires on Tuesday, alongside the risk of intense gusts, hail and torrential downpours.
In the evening, these showers will merge into a more organised band of heavy rain that will push north-eastwards through the night, led by a cold front. Argentina’s national weather service has issued a yellow alert for storms, warning of up to 30-50mm of rainfall in 12 hours.
The front will clear by midday on Wednesday, leaving behind cool, dry conditions, with daytime temperatures peaking in the mid-teens. There could be a very small variation in temperatures between the mild Tuesday night and cool Wednesday, with the chance of diurnal temperatures of about 1-1.5C in Buenos Aires and perhaps Rosario, a range that is typically 10-12C.
On the opposite side of the Pacific Ocean, there is a storm brewing. Tropical Storm Nari, situated to the south-east of Japan, will propagate north-westwards towards the country by Monday morning and deepen into a severe tropical storm, which is defined as having a maximum wind speed of 55-73mph (89km/h to 117km/h).
Nari is forecast to travel adjacent to the north-east coast, bringing sharp showers and heavy rain. The Japan Meteorological Agency has forecast wind advisories for much of the Kanto region, alongside 50-100mm of rainfall within a 24-hour period.
