This link will help you understand Synesthesia
Yes, Mondays are blue. Specifically French blue. Every day of the week has its own color. Sunday is golden yellow, Tuesday is a yellow-ochre, Wednesday is indigo blue and sometimes changes to blue violet, Thursday is burnt orange, and Friday is solid wood brown, and of course Saturday is rich pure red while Mondays are not just any blue… they are French blue. I learned the names of these colors from being a painter and using oil paints. I experience these colors every week and they help me maintain the calendar in my stupid old head. I began to realize when I first heard about the colors of the wind in the Disney movie Pocahontas that there was something to this everyday thing, something different in the way I see the world. I have in the last few years learned that this condition has a name. It is called synesthesia.
It has been suggested to me by more than a few people that I don’t really perceive the world the same way “normal people do”. When I was growing up, and going to school, I never had trouble remembering to capitalize the first word in a sentence. I did however, have a great deal of difficulty with capital letters on nouns. Looking back on that difficulty now, I can say without a doubt that I was having trouble not because I didn’t know the difference between proper nouns and common nouns. It was because things like the word “dog” or “chair” had to begin with the right color. Dogs are blue when you are talking about the color of the letters in the word. But small “d” is blue-green, not true blue. It doesn’t fit as well as the dark blue capital “D”. And chairs are orange-red when you write them down, while the small “c” appears light green by itself.

Sundays are Sun-days, and that’s why they are golden yellow.
I am told that most synesthetes are taken by surprise when they learn that they are seeing things differently than other people do. I certainly was. I always got funny looks whenever I described Thursdays as orange, or the month of November as sky blue. My classmates in 4th grade thought I was nuts… of course, it wasn’t just for the orange Thursdays thing. I was not a normal kid in any real sense of the word. I always suspected that if I could look at the world through other people’s eyes, I would probably see the color green as what I called red, or that glowing halo that surrounded things when organ music played in the Methodist church would no longer be there. But once I learned how synesthesia works I knew it was true. The visual part of the brain can be scanned to show activity, and lights up on the scanner as if the brain is seeing bright colors when Beethoven’s Ninth Symphony is being played while the subject of the scan is actually blindfolded. I am told that synesthesia is more common in left-handed girls. My daughter, the Princess, tells me that she also sees color on printed numbers and letters. She is left handed and also gifted at drawing. I suspect she inherited the synesthesia from me.

Synesthesia probably explains what this nonsense is all about.
Now, I acknowledge the fact that my synesthesia is self-diagnosed and not proven by any of the methods the articles I have read about the condition talked about. But my personal experiences always seem to fall in line with descriptions of letter/number/color combinations and music/color combinations that I have read about. And if I do have it, it is not the same as any of my six incurable diseases. It is not a bad condition to have. In an artistic sense, it might actually be a good thing. I could use some good for a change. Good doesn’t usually come from weirdness… not my weirdness, anyway. (Oh, and capital “G” is lime green… as is the word Goodness).