As the atmosphere transitions into the colder months, the passage of cold fronts will become more frequent. This weekend the coldest air of the season is set to invade western Kansas. Even if freezing temperatures don't materialize, eventually a cold airmass capable of ending the growing season will arrive across Kansas. On average the first 32 degree temperature will occur in the first three weeks of October across the region. However, this date can change significantly from year to year. A "killing" freeze (temperatures of 28 degrees or colder) typically occurs, on average, about 10 days later. Some locations (like Ashland) are heavily influenced by topography and local effects.
So, if freezing temperatures do occur this weekend (which it's becoming a little more likely), the occurrence would be ahead of schedule.
(click on the maps or graphs for a larger version)
The following graph shows when the first 32 degree temperature during the Fall was observed at Dodge City (1948 through 2010). The bar graph depicts the number of occurrences during the 7 day period. The area graph (blue) shows the percentage of all the occurrences, i.e. 75 percent of all years the first 32 degrees was observed on or before October 26. During the fall of 2012, the first 32 degrees at Dodge City occurred on October 20th.