Weather in Baltimore in January 2018. Expect 5°C daytime maximum temperatures in the shade with on average 5 hours of sunshine per day in Baltimore in January. Check more long-term weather averages for Baltimore in January before you book your next holiday to Maryland in 2018. 1  Baltimore weather overview. 2  Baltimore monthly weather. 3  Baltimore 5-day forecast. 4  Maryland holidays. 5  Maryland map. 6  More destinations. 7  Back to Maryland.