Could they be wearing Easter bonnets? The hats seem pretty fancy. Easter was on March 24 in 1940 and on April 13 in 1941. Which date is more likely for the cherry blossoms?
The photos are really sharp. I am guessing someone in that family owned a proffesional camera, maybe a 4X5 inch sliding plate type.
Cherry Blossoms are around late March to the middle of April. Yes, a very professional camera. I don’t know about Easter bonnets because everyone wore hats back then but they are very nicely dressed, so good guess.