Mendoza weather in September

September in Mendoza is winter ending rather than spring arrived: good for sightseeing, the wineries open and taking visitors, and evenings still genuinely chilly. The mountains are the part to plan around - the upper Andes, Aconcagua included, can still be a problem this early, so that end of a trip is the one to keep flexible. The local hazard is the zonda, the hot dry wind off the mountains, which blows in every month of the year and can cut a winery tour short on the day it arrives. Our row shows the dryness behind it: 44.7 percent humidity and a dew point of 0.2C. The record: 22.8C days that feel like 20C, 8.8C nights, 2.9 precipitation days carrying 11.3mm, 10.6 hours of sun and a 16 kph wind.

Regulars are specific this counts as a genuinely dry, hot month here, part of a broader pattern that gives the region over 320 sunny days a year and just 7 to 8 inches of rain total annually. Our row backs that hot, genuinely dry read, 30.9C reading as a hot 31C, over 17.9C nights feeling 16C, with rain minimal at 26.8mm across 4.3 days and humidity down to 41 percent. Regulars are consistent mid-December specifically gets singled out as a good window for wine touring and day trips into the nearby Andes, the dry heat here reading very differently from a humid summer elsewhere. Sun protection remains genuinely necessary given how many clear days are typical. The record: 12.7 hours of sun, an 18.6 kph wind and AQI 33.

August is winter here and the board is relaxed about it: not really cold down in the valley, days around sixty Fahrenheit, which is our feels-like high of 15C almost exactly, against nights that touch freezing at 5.4C reading as 2C. The cellars do not close - wineries run tours all year, and August brings ski traffic through the city, so plenty is open. What changes is how the place looks: the vines and trees are bare, and regulars insist the landscape is worth the drive anyway. The air is dry at 50.6 percent with 19.3mm of rain across 3.8 days, and remarkably clean at AQI 31. The record: 9.5 hours of sun and a 14.3 kph wind.

March is the month regulars name for Mendoza - warm but no longer hot, the vines turning colour, and the harvest running through it - but the question they get asked is which week, and their answer is practical. The Fiesta Nacional de la Vendimia falls on the first Friday of March, and that week means guaranteed reservations or none at all, higher prices for beds, transport and food, and show tickets that sell out and climb as the date nears. The rest of the month is the same weather without the squeeze. Our row reads 28.5C over 16.5C at 55 percent humidity, with 39mm across 6.5 days. The record: 10.5 hours of sun, a 15.2 kph wind and AQI 29.

Mendoza regulars describe October to May as the warm run and single out November for being outdoors, with the Valle de Uco at its best. Our row is high-desert weather at 28.9C by day and 15.4C at night, 42 percent humidity and 12.5 hours of sun - dry enough that the afternoon never feels hotter than the thermometer and the evening drops thirteen degrees. The local name to know is the zonda, a hot dry wind coming down off the Andes that can cut a winery tour short; our 18.3 kph is the month averaged and says nothing about the day it arrives. On timing, the Vendimia runs events from late November through to April, but the main week is the end of February into early March, not now. The record: 28.9mm across 5.4 precipitation days and AQI 31.