About polish climate
The climate is mostly temperate throughout the country. The climate is oceanic in the north and west and becomes gradually warmer and continental towards the south and east. Summers are generally warm, with average temperatures between 18 and 30 °C (64.4 and 86.0 °F) depending on a region. Winters are rather cold, with average temperatures around 3 °C (37.4 °F) in the northwest and ?6 °C (21 °F) in the northeast. Precipitation falls throughout the year, although, especially in the east; winter is drier than summer.98
Źródło: https://en.wikipedia.org/wiki/Poland#Climate
Where to spend picnic
May weekend is one of the first opportunities for short tourist trips. Picnic can spend not only a home barbecue, but also for mountain walks or visiting Polish monuments of nature, and above all walks of large parks and greenery around the beautiful lakes. This way you can not only eat well, but also to spend time in the fresh air and the opportunity to see the history of Polish tourism. Weather in early May is sometimes different, but certainly much more conducive to family walks in the mountains, than the weather prevailing during the cold weather. In contrast, people who visit the large parks, may in designated areas also organize family camping.
Some facts about Cracow
Kraków (Polish pronunciation: ?krakuf About this sound listen (help?info)), also Cracow or Krakow (US English /?kr??ka?/, UK English /?kr?ka?/),23 is the second largest and one of the oldest cities in Poland. Situated on the Vistula River (Polish: Wisła) in the Lesser Poland region, the city dates back to the 7th century.4 Kraków has traditionally been one of the leading centres of Polish academic, cultural, and artistic life and is one of Poland's most important economic hubs. It was the capital of the Crown of the Kingdom of Poland from 1038 to 1569; the Polish?Lithuanian Commonwealth from 1569 to 1596;5 the Free City of Kraków from 1815 to 1846; the Grand Duchy of Cracow from 1846 to 1918; and Kraków Voivodeship from the 14th century to 1998. It has been the capital of Lesser Poland Voivodeship since 1999.
The city has grown from a Stone Age settlement to Poland's second most important city. It began as a hamlet on Wawel Hill and was already being reported as a busy trading centre of Slavonic Europe in 965.4 With the establishment of new universities and cultural venues at the emergence of the Second Polish Republic in 1918 and throughout the 20th century, Kraków reaffirmed its role as a major national academic and artistic centre. The city has a population of approximately 760,000, with approximately 8 million additional people living within a 100 km (62 mi) radius of its main square.6
Źródło: https://en.wikipedia.org/wiki/Krak%C3%B3w