[Summer Squall is] one of his characteristic marines. . . . His method is entirely his own. He paints nature as he sees it—always, however, seeing it with a lively appreciation of all that is picturesque and dramatic. His command of the local color and spirit of a scene is always masterly, and his works reveal an ability to grasp dominant characteristics and to reproduce specific expressions of scenes and sitters; for this reason it is that no two of Homer’s pictures look alike. His every canvas bears the reflex of a distinct artistic impression.

— “Paintings at Carnegie Galleries, No. 7,” [Pittsburgh] Gazette, 6 Dec. 1904
Captain Thomas Boynton, who owned a small sailboat, had taken some young children out on the bay. Without warning a sudden squall struck violently, accompanied by torrential rain and a gusty wind that blew the chairs off the porch of the Checkley House [a hotel on Prout’s Neck], next door to the Ark [the Charles Homer family house]. . . . Winslow had put on his heavy raincoat and gone down to the shore. Captain Boynton, who knew the hazards of a lee shore, had put out away from the dangerous cliffs of the Neck to ride out the storm in safer, open water. . . .
The unusual and spectacular squall made a deep impression on all those who were there, especially Winslow and his family, who had joined him on the shore. As they were walking back to the Ark, Charles said, ‘He’ll have that on canvas soon.’ He was quite right; his brother retired to his studio and was furiously busy for several days. About two weeks later he came into the Ark carrying the nearly completed painting. . . .
According to Homer’s nephew Charles, the artist could not immediately complete the painting to his satisfaction and kept it for several years in a closet in the studio. Finally, in 1904, he added the last touches, and signed and dated it that year.

—Philip C. Beam, Winslow Homer at Prout’s Neck (Boston: Little, Brown and Co., 1966)
On December 20, 1901, Homer wrote to his dealer: “Do not think that I have stopped painting. At any moment I am liable to paint a good picture.” But it seems that, for the next several years he did not paint with oils very much—travel, watercolors, fishing, illness—all kept the sexagenarian from starting major oils until late in 1904. He did touch up several older works during the period. Summer Squall, which was on Homer’s easel in March 1904, evidently falls into this category; the Homer family recounted that it was largely painted in 1896. Even with that good start, it was not an easy project. Homer wrote of it from Prout’s Neck in May 1904: “It has been so cold & wet here that paint would not dry—& I had all I could do to keep alive. I now send you by American Express the painting—‘Summer Squall.’”
Summer Squall is one of Homer’s most elemental canvases: waves break over a rock in the foreground, the amount of aerated foam suggesting the force of the stormy sea; patchy fog enfolds the distant view and almost blocks the morning sun. In the distance a small boat, with sail snapping free, rushes away from shore. The weather is fierce enough to confuse even the elemental question of a horizon line, although, when seen from ten or more feet away, Homer’s carefully articulated veils of mist and fog allow a ready sense of depth to inflate the scene.
The site is at Prout’s Neck, Maine, and the foreground rock one that, in calmer weather, Homer fished from. Witnesses (as noted by Beam, above) reported that the picture was inspired by an incident in 1896: a dory with small children out for a summer sail was caught in a notably sudden and violent squall. When the sailor, aware of the dangers of coming too close to the shore, headed out to sea, the mothers on shore feared that he was being driven by the storm. Homer was able to assure them that the man was doing the sensible thing by waiting out the squall on more open water. All returned safely. (Recent scholars have reasonably pointed out that the stories reported to Beam in the 1940s were recalled from decades in the past and could have been subject to a natural embellishment on the tellers’ parts.)
Summer Squall is smaller than most of Homer’s late seascapes, and he asked a correspondingly modest price for it—to net him $700 rather than the $1,000 that he settled for with Eastern Point two years earlier. Yet he thought enough of the painting to send it to the Carnegie Institute’s annual exhibition in 1904, the nation’s most important contemporary art show. The picture received favorable reviews there and was exhibited once more in 1914. After that, however, it was not seen again by the public until the inauguration of the Sterling and Francine Clark Art Institute in 1955.

—Marc Simpson, curator of Winslow Homer: Making Art, Making History and curator of American art at the Sterling and Francine Clark Art Institute