Welcome to breakup! It's in the high 30's, a new tide book is published, and the world is turning to ice and mud - in a month, maybe less, green things will start to grow! But as the seasons turn, so familiar landing places become unfamiliar again.
In the spring where mud flats are exposed at low tide, ice cakes moving with the current will drag in the mud. The depth of the grooves left depends on the size of the ice cake, consistency of mud, etc. Strong currents will not only erase these grooves, but also carry away the finest particles that make soft mud, while weak currents leave evidence of grooves and the softest mud. Ergo, if you see ice grooves in the mud after the ice has been gone a while, don't land.
As the spring goes on, ice chunks buried in the sand and gravel on a sea beach will be melting, making for some spots so soft they'll trip an airplane. Fly very low along any intended beach and look for the tell of slight depressions in the sand.
Convex curved sea beaches are usually steeper and more uneven than concave ones - this is important, pay attention. Centrifugal force pulls the airplane toward the water and the roughness reduced the wheel's hold on the beach. Also, in a 3-point attitude, like when you finally get her planted on, the weight of the tail drags it downhill, turning the plane uphill toward the driftwood trees tossed at the high-tide line. If tide, weather, daylight, etc permit, early afternoon landings and takeoffs may be safer as the inland sea breeze will help counteract all of this.
When the tide comes in, it comes up through the mud flat and the sandbar, as well as in from the ocean. Your landing strip will not only get smaller, it will get softer and soupier before the visible tide reaches it. Always leave yourself a margin for deteriorating conditions, and take off before the water comes close to your tires.