Yes

you do need a jacket based on the weather in Waukesha, WI, USA 1 second ago

Why? Because the cold's there, but it's just a reminder, not an invasion!
38°F3°C & Cloudy

Wind is 5 mph8 km/h from the Southeast, gusting to 12 mph19 km/h
December 26
11am38°F3°C6 mph9 km/h SoutheastCloudy
12pm39°F4°C6 mph10 km/h SoutheastCloudy
1pm40°F5°C7 mph10 km/h SoutheastCloudy
2pm42°F5°C6 mph10 km/h SoutheastHaze
3pm42°F6°C5 mph8 km/h SoutheastHaze
4pm42°F6°C4 mph7 km/h SoutheastCloudy
5pm41°F5°C5 mph8 km/h SoutheastCloudy
6pm41°F5°C6 mph9 km/h SoutheastCloudy
7pm40°F4°C6 mph9 km/h SoutheastCloudy
8pm40°F4°C6 mph10 km/h SoutheastCloudy
9pm40°F5°C7 mph11 km/h SoutheastCloudy
10pm41°F5°C7 mph11 km/h SouthCloudy
DateLowHighWindDayNight
December 2634°F1°C42°F6°C5 mph8 km/h from SoutheastHazeCloudy
December 2739°F4°C45°F7°C10 mph16 km/h from SoutheastRainRain
December 2839°F4°C47°F9°C11 mph18 km/h from SouthwestMostly CloudyMostly Cloudy
December 2936°F2°C43°F6°C7 mph11 km/h from WestCloudyMostly Cloudy
December 3033°F1°C41°F5°C5 mph7 km/h from SouthwestCloudyCloudy
December 3128°F-2°C36°F2°C12 mph20 km/h from NorthwestSnowMostly Cloudy
January 122°F-6°C29°F-2°C14 mph23 km/h from WestCloudyPartly Cloudy

Yes

Low of 39°F4°C, High of 45°F7°C
Wind: 10 mph16 km/h
Precipitation: 66% rain

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