Buenos Aires Weather

Climate
Buenos Aires has a humid subtropical climate (Köppen Cfa), with very humid summers and mild winters. The warmest month is January, with a daily average of 25.1 °C (77.2 °F). Most days see temperatures in the 28 to 31 °C (82 to 88 °F) with nights between 16 to 21 °C (61 to 70 °F). Heat waves from Brazil can push temperatures above 35 °C (95 °F), yet the city is subject to cold fronts that bring short periods of pleasant weather and crisp nights. Relative humidity is 64–70% in the summer, so the heat index is higher than the true air temperature. The highest temperature ever recorded was 43.3 °C (110 °F) on 29 January 1957. Spring (September to November) and autumn (March to May) are generally mild and volatile, with averages temperatures of around 17 °C (63 °F) and frequent thunderstorms, especially during the spring.

Winters are temperate, though suburban areas often experience frost from May to September, as opposed to downtown Buenos Aires, which experiences the phenomenon only some times per season. Relative humidity averages in the upper 70s%, which means the city is noted for its moderate to heavy fogs during autumn and winter. July is the coolest month, with an average temperature of 10.9 °C (51.6 °F). Cold spells originating from Antarctica occur almost every year, and combined with the high wintertime humidity, conditions in winter may feel much cooler than the measured temperature. Most days peak reach 12 to 17 °C (54 to 63 °F) and drop to 3 to 8 °C (37 to 46 °F) at night. Southerly winds may keep temperatures below 10 °C (50 °F) for a few days, whereas northerly winds may bring temperatures above 20 °C (68 °F) for a few days; these variations are normal. The lowest temperature ever recorded in central Buenos Aires (Buenos Aires Central Observatory) was −5.4 °C (22 °F) on 9 July 1918. The last snowfall occurred on 9 July 2007 when, during the coldest winter in Argentina in almost 30 years, severe snowfalls and blizzards hit the country. It was the first major snowfall in the city in 89 years. On 17 July 2010, in the midst of another cold winter, flurries struck the southern reaches of Buenos Aires, but not the central parts as occurred in 2007 or 1918.

Spring is very windy and variable: there may be heat waves with temperatures of 35 °C (95 °F) even in early October, as well as periods of much colder weather with highs close to 10 °C (50 °F). Frost has been recorded as late as early November, although this is unusual. Severe thunderstorms are likely between September and December.

The city receives 1,242.6 mm (49 in) of rainfall per year. Rain can be expected at any time of year and hailstorms are not unusual.

source: wikipedia