Chilly weather this week

It has been rather chilly especially in the morning here in Yuma.  It feels as though I am living somewhere else, like Santa Barbara, CA, instead of in Arizona. Here's a link into Yuma's monthly weather for October, http://www.weather.com/weather/monthly/USAZ0275.  As you can see there was a dramatic decline in temperature from October 4 to the 5 and also from October 17 to 18.   What is ironic is that we have had an abnormal high temperature for the month of October and also an abnormal low temperature.  The cold weather has me already thinking about Christmas, matter of fact, just yesterday I went to Target to buy a couple of pine scented candles.  It seems as though this winter will be much colder than ones that I've experienced in Yuma.  My first year in 2005 was pretty chilly but other years were sort of warmer and wetter.  I know in class we discussed La Nina and El Nino, and right now we are experiencing La Nina. It's forecast that we will have a drier and warmer Christmas, but I am going to have to disagree with a portion of that statement.  I believe we will have a drier Christmas but I feel that this year will be much chillier. So, what exactly is causing such a dramatic decline in temperature for us this year?  I tried researching it but came up empty.  My prognosis is that we are experiencing a cold front a lot earlier this year from northern Canada or Alaska. But, I believe "usually" rain is associated with the cold front that comes from up North every winter. However, I am grateful for an early break from the hot weather we were experiencing in the beginning of October. Hopefully we will have great weather for a while, that is until July comes around.