Recent changes in Moscow's regional climate, since it is in the mid-latitudes of the northern hemisphere, are often cited by climate scientists as evidence of global warming, though by definition, climate change is global, not regional. During the summer, extreme heat is often observed in the city (2001, 2002, 2003, 2010, 2011). Along with a southern part of Central Russia, after recent years of hot summer seasons, the climate of the city gets hot-summer classification trends. Winter also became significantly milder: for example, the average January temperature in the early 1900s was , while now it is about . At the end of January–February it is often colder, with frosts reaching  a few nights per year (2006, 2010, 2011, 2012, and 2013).