Well ya see Mr Laz, concealed carry does work to reduce crime and protect innocents but it does take time.
Time for people to get the permits and time for the crimes to occur.
According to this site which tracks the murders http://homicides.suntimes.com/suspects/ only 18 of the suspects in the last 100 murders were white. 4 of the last 100 victims were white. The rest are predominantly black with a small number of hispanics.
A map of the murders show most of them are in the inner city urban area http://homicides.suntimes.com/homicides/map/2014/
And page 16 of this report on murders by Chicago PD for 2010 shows the murder rate for summer months is higher then winter months. https://portal.chicagopolice.org/portal/page/portal/ClearPath/News/Statistical%20Reports/Murder%20Reports/MA10.pdf
but I could be wrong.
However, I do agree winter was a factor.