Does a tan change your season?
I think this must be up there in the top ten questions asked of colour analysts. Even the most sunscreen-committed of us tend to see some variation in our skintone throughout the year - from winter's palest shades through the first hint of colour as Spring appears and then on to our own personal deepest tan by the end of the summer. Personally I experience this in extremes, with my father's fair Scottish heritage predominating during winter and my mother's more olive-skinned genes taking over once the sun comes out, so as a client it was top of my list of questions when I had my own colour analysis and which my consultant gave an almost identical answer to the one I am going to give you here.
The - very - short answer is no. Not only does your season does not change throughout the year, it actually remains unchanged throughout your entire life, but that's further than we need to worry about today. Colouring is determined by genetics, and remains unchanged regardless of (natural) tanning, scars, ageing etc.
Rather than ending there, I suppose it's only fair to also give you the longer answer too. When you had your colour analysis, the chances are you were given some kind of 'direction' within your season, being described as a light Spring, or a deep Summer, or similar applicable adjective. So as well as being given a broader palette you will also have been guided as to what your 'wow' colours are within that palette.
When we are at our palest (and therefore often our least 'bright', regardless of how bold or muted our personal palette is), we often rely on our wow colours more, feeling less confident in other parts of the palette. However, as we get more colour in our own skin, some of those less good colours seem to start working too. The reason is that tan does some of the work, adding a bit of a glow and hiding some imperfections, so we are able to venture outside our wow colour comfort zone a little more and wear just 'good' colours as well as wow ones. As an aside, most people are more comfortable wearing brighter colours when it's sunny and bright outside, so there is a psychological correlation between feeling confident with the brighter colours in warmer weather too.
So, in summary, a tan will never affect your seasonal outcome, but it may affect how you look and feel in some of the less wow colours within your palette.
A note about fake tan: almost all fake tan is warm (yellow) toned, and can seriously alter the outcome of a colour analysis, because it adds an artificially warm overtone to the skin. This is especially true, obviously, of cool toned people, but can alter the wow colour outcome even for the warmer toned among us.