Group Boxplot with multiple Y variables

Hi every one

I am new to the this R community. I have 30 years monthly Tmax data from three different sources which I called as Baseline, TmaxRCP2.6 and TmaxRCP8.5. i want to create a boxplot for all the three sources with respect to each month. which means every month will have three boxplots side by side ie (Baseline, TmaxRCP2.6 and TmaxRCP8.
I will really appreciate any help in this regard.

Can upload the data as it is to lengthy but an example is given below:

Month Baseline TmaxRCP2.6 TmaxRCP8.5
Jan
.
.
.
.
.
Feb.
.
.
.
.
.
Mar
.
.
Until
.
.
. Dec

Not sure if this helps, but you might look at something like:

install.packages("palmerpenguins")
library(palmerpenguins)
boxplot(body_mass_g~sex+species, data=penguins, frame=F, col = c("#00AFBB", "#E7B800"), names=c("Adelie.F", "Adelie.M", "Chnstrp.F", "Chnstrp.M", "Gentoo.F", "Gentoo.M"))

I think the format of your data frame would need to change to something like:

Month | Reading | Value
Jan TmaxRCP2.6 ...
Jan TmaxRCP2.6 ...
Jan TmaxRCP2.6 ...
Jan TmaxRCP8.5 ...
Jan TmaxRCP8.5 ...
Jan TmaxRCP8.5 ...
or similar