Yes

you do need a jacket based on the weather in 11-041 Olsztyn, Poland 1 second ago

Why? Because a jacket will keep you cozy, but you won't break a seat!

58°F15°C & Cloudy

Wind is 7 mph12 km/h from the Northwest, gusting to 16 mph25 km/h

Date	Low	High	Wind	Day	Night
May 18	38°F4°C	58°F15°C	5 mph9 km/h from Northwest	Mostly Cloudy	Partly Cloudy
May 19	43°F6°C	68°F20°C	9 mph14 km/h from West	Mostly Clear	Mostly Clear
May 20	47°F8°C	69°F20°C	9 mph15 km/h from Southwest	Mostly Clear	Mostly Cloudy
May 21	48°F9°C	63°F17°C	10 mph16 km/h from Southwest	Mostly Cloudy	Mostly Cloudy
May 22	44°F7°C	58°F15°C	7 mph11 km/h from West	Mostly Cloudy	Mostly Cloudy
May 23	44°F6°C	60°F15°C	8 mph13 km/h from Southwest	Partly Cloudy	Partly Cloudy
May 24	45°F7°C	61°F16°C	8 mph13 km/h from Southwest	Mostly Cloudy	Partly Cloudy

Low of 43°F6°C, High of 68°F20°C
Wind: 9 mph14 km/h
Precipitation: None