converting month and day column to corresponding numbers in R and divide table into 2 matrices

I am reading data from UCI repository into table.

forestfire <- read.table(file = "http://archive.ics.uci.edu/ml/machine-learning-databases/forest-fires/forestfires.csv", 
                         header = TRUE, sep = ',')

How can I convert month and day column to corresponding numbers? I also want to divide this table to 2 matrices.