Climate

Austria, located in the European heartland, lies within a temperate climatic zone. Austria’s landscapes include major and minor mountain ranges, hills and plains. 

Weather conditions vary only slightly across the country, the lowland regions in the north and east have more continental influenced conditions with colder winters and hotter summers with moderate precipitation throughout the year. The southeastern areas of Austria have longer and warmer, almost Mediterranean-like summers. 

In the western part of the country the influence of the temperate Atlantic climate is felt more strongly. Consequently, this part is subject to less extreme weather conditions; winters are usually mild and summers rather warm. The west is also characterized by high precipitation. The diversity of topographical and climatic conditions results in a very versatile flora and fauna.

The geographic features in the more mountainous regions of the country have given rise to yet another climate zone, the Alpine climate, which causes winters to be colder than at lower altitudes. Temperatures depend largely on altitude, with averages 41 degrees Fahrenheit (5 degrees Celsius) lower for each additional 985 ft (300 m) of elevation. The country’s highest mountain is the Grossglockner (3,797m or 12,457 ft). Be aware that whatever the season, if you're at a high altitude, the weather can change quickly and dramatically. 

Temperatures 
The coldest month in Austria is usually January. The winter snow cover lasts from late December through March in the valleys, from November through May at about 5,905 ft or 1,800 m, and becomes in many years permanent above about 8,202 ft or 2,500 m. Temperatures begin to rise again in February. In March, temperatures may rise up to 54 degrees Fahrenheit (12 degrees Celsius). Summers can be hot, with temperatures sometimes reaching 86 degrees Fahrenheit (30 degrees Celsius) or more (maximum temperatures revolve around around 95 degrees Fahrenheit or 35 degrees Celsius in July). Summer evenings are usually cool.

Precipitation 
Precipitation is quite evenly distributed over the entire year. However, the months May, September and the first half of October tend to be the driest; April and November tend to be the wettest periods.  

Again, altitude determines the precipitation pattern; while high-level areas in the Alps may have a high average rainfall in excess of 2000 mm per year, while some regions in the flatlands of Austria have only 600 mm annually. From June through August, rain usually comes in the form of sometimes heavy thunderstorms, these storms can bring heavy hail and snowfall in the mountainous regions of the Alps, even in summer.

Required clothing 
Lightweights with rainwear for summer, waterproof Medium- to Heavyweights for winter. A sweater is necessary almost any time of year.

Koeppen-Geiger Classification 
The climate of Austria can be classified as Cfb Climate; a warm temperated humid climate with the warmest month lower than 72 degrees Fahrenheit (22 degrees Celsius) over average and four or more months above 50 (10 degrees Celsius) over average. The climate of the Mountainous Regions of Austria can be classified as Dfb Climate; a humid snow climate with the warmest month between 50 and 72 degrees Fahrenheit (10 – 22 degrees Celsius), the coldest month below 26 degrees Fahrenheit (-3 degrees Celsius) and at last four or more months above 50 degrees Fahrenheit (10 degrees Celsius). 

Source: http://www.weatheronline.co.uk/reports/climate/Austria.htm