To create a "drop down menu" you can use OptionMenu in tkinter
Example of a basic OptionMenu:
from Tkinter import *
master = Tk()
variable = StringVar(master)
variable.set("one") # default value
w = OptionMenu(master, variable, "one", "two", "three")
w.pack()
mainloop()
More information (including the script above) can be found here.
Creating an OptionMenu of the months from a list would be as simple as:
from tkinter import *
OPTIONS = [
"Jan",
"Feb",
"Mar"
] #etc
master = Tk()
variable = StringVar(master)
variable.set(OPTIONS[0]) # default value
w = OptionMenu(master, variable, *OPTIONS)
w.pack()
mainloop()
In order to retrieve the value the user has selected you can simply use a .get() on the variable that we assigned to the widget, in the below case this is variable:
from tkinter import *
OPTIONS = [
"Jan",
"Feb",
"Mar"
] #etc
master = Tk()
variable = StringVar(master)
variable.set(OPTIONS[0]) # default value
w = OptionMenu(master, variable, *OPTIONS)
w.pack()
def ok():
print ("value is:" + variable.get())
button = Button(master, text="OK", command=ok)
button.pack()
mainloop()
I would highly recommend reading through this site for further basic tkinter information as the above examples are modified from that site.