change the order of a common legend, in a superimposed graph - r

Question

I would like to change the order of my legend, and not to display them in alphabetical order as you can see below. I would like to have
"NONE","LIGHT","MEDIUM","HEAVY","V_COLD","COLD","MEDIUM","HOT".
Is it possible? I tried with several arguments but without success.
Below, my table :
structure(list(SOUNAME = structure(c(1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = "BALLYSHANNON (CATHLEENS FALL)", class = "factor"),
year_month = structure(c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L,
3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 6L, 6L, 6L,
6L, 7L, 7L, 7L, 7L, 8L, 8L, 8L, 8L, 9L, 9L, 9L, 9L), .Label = c("2013-03",
"2013-04", "2013-05", "2013-06", "2013-07", "2013-08", "2013-09",
"2013-10", "2013-12"), class = "factor"), pre_type = structure(c(4L,
1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L,
4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L,
3L, 4L, 1L, 2L, 3L), .Label = c("HEAVY", "LIGHT", "MEDIUM",
"NONE"), class = "factor"), pre_value = c(13L, 2L, 11L, 5L,
9L, 3L, 10L, 7L, 2L, 6L, 13L, 10L, 10L, 1L, 15L, 4L, 16L,
2L, 7L, 5L, 2L, 2L, 17L, 9L, 7L, 3L, 13L, 6L, 5L, 2L, 10L,
14L, 1L, 5L, 19L, 6L), tem_type = structure(c(4L, 3L, 2L,
1L, 4L, 3L, 2L, 1L, 4L, 3L, 2L, 1L, 4L, 3L, 2L, 1L, 4L, 3L,
2L, 1L, 4L, 3L, 2L, 1L, 4L, 3L, 2L, 1L, 4L, 3L, 2L, 1L, 4L,
3L, 2L, 1L), .Label = c("COLD", "HOT", "MEDIUM", "V_COLD"
), class = "factor"), tem_value = c(0L, 7L, 0L, 23L, 0L,
29L, 0L, 1L, 0L, 29L, 2L, 0L, 0L, 21L, 9L, 0L, 0L, 5L, 25L,
0L, 0L, 18L, 13L, 0L, 0L, 21L, 9L, 0L, 0L, 26L, 5L, 0L, 0L,
24L, 0L, 7L), cnt_vehicle = c(NA, 2754406, NA, NA, NA, 2846039,
NA, NA, NA, 3149377, NA, NA, NA, 3058810, NA, NA, NA, 3362614,
NA, NA, NA, 3415716, NA, NA, NA, 3020812, NA, NA, NA, 3076665,
NA, NA, NA, 2775306, NA, NA), x = c(1L, 1L, 1L, 1L, 2L, 2L,
2L, 2L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 6L,
6L, 6L, 6L, 7L, 7L, 7L, 7L, 8L, 8L, 8L, 8L, 9L, 9L, 9L, 9L
)), .Names = c("SOUNAME", "year_month", "pre_type", "pre_value",
"tem_type", "tem_value", "cnt_vehicle", "x"), row.names = c(NA,
-36L), class = "data.frame")
Below my graph:
ggplot(data = b_complet_2013, aes(x = x, y = pre_value*100000, fill = pre_type), stat = "identity") +
scale_x_continuous(breaks=(1:9)+0.2, labels=unique(b_complet_2013$year_month)) +
geom_bar(stat = "identity", width=0.3) +
xlab("date") + ylab ("Number of days of précipitations(left) and temperatures (ritght)") +
ggtitle("Precipitation per month") +
geom_bar(data=b_complet_2013,aes(x=x+0.4, y=tem_value*100000, fill=tem_type), width=0.3, stat = "identity") +
xlab("date") + ylab("Number of days of precipitations(left) and temperatures (ritght)") +
ggtitle("Impact of weather on road traffics") + theme( axis.title.y = element_text(color = "blue", face = "bold")) +
theme(axis.text.y = element_text(color = "blue", face = "bold", size=9)) + theme( axis.title.y.right = element_text(color = "black", face = "bold")) +
theme(axis.text.y.right = element_text(color = "black", size = 9, face = "bold")) +
geom_line(mapping = aes(x= x+0.2, y = as.numeric(cnt_vehicle)), colour = I("blue"), size = 0.8) +
geom_point(aes(x= x+0.2, y = as.numeric(cnt_vehicle), colour = I("blue")), show.legend=FALSE, stat = "identity") +
scale_y_continuous(sec.axis = sec_axis(~./100000,name="Number of days of precipitations(left) and temperatures (ritght)")) +
theme( plot.title = element_text(size = 17)) + theme(axis.title.x = element_text(size = 12)) + theme(axis.title.y = element_text(size = 12)) +
labs(y = "Number of vehicles", color ="black") +
theme(panel.background = element_rect(linetype = "dashed", fill="white"), plot.background = element_rect(linetype = "dashed",fill="grey90" ))