A technique mastered by English artists since the 18th century, producing watercolours in the open air, from life, developed in France in the second half of the 19th century, helped by the emergence of new equipment and ready made paints. In the tradition of the English school, the technique was highly codified with a set of rules. Watercolour painting evolved in France, and, through the widespread influence of William Turner, and above all the vital contribution of Eugène Boudin and Jongkind, it was transformed into a very free genre, and revolutionised. In parallel with this, a picturesque, academic style continued, mainly supported by the Society of Watercolourists.
At the end of the 17th century, the practice of producing studies from life had been introduced into the programme and the philosophy of traditional Academic teaching. More practical than oils, better able to respond to the constant challenge of unpredictable, natural settings, watercolours replaced oils at an opportune moment, as much for the painters still loyal to the neo-classical tradition as for those who were breaking free from it. In the summer of 1888, Camille Pissarro encouraged Signac to take up watercolour, praising its suitability for the demands and constraints of painting from life: "It is invaluable and very practical; in a few minutes you can take notes which would be impossible otherwise – the fluidity of a sky, certain transparencies, numerous pieces of information that hours of work would never give you, as the effects are so fleeting". Years later, Signac confirmed how pertinent this advice had been, and, in his monograph on Jongkind, added the comment, "Watercolour is just a method of making notes, a sort of memorandum, a rapid and productive process enabling the painter to increase his repertoire of elements too short-lived to be captured by the slow process of oil painting. A cloudy sky is a magnificent subject, but is constantly changing […]".