Is he asking about your weekend or just making conversation?

The same question means different things depending on what came before. If he's been asking you things all week, remembered a detail from last time, or brought up a plan you made, then asking about your weekend is part of a pattern and probably sincere. If this is the first real exchange, or the messages so far have been short and logistical, it's more likely a standard opener. Check whether he's offered anything about himself. People who want to know about your life usually share a bit of theirs, even just a line about what they got up to, because they're inviting you into a back and forth.

Also look at the timing. A weekend question sent Monday morning after a quiet few days reads as a deliberate check-in. The same question sent Friday afternoon, when everyone is asking everyone about their plans, is probably just the default for the moment. Neither settles it, but together they give you a much better read than the words alone.

The best reply is short but concrete. A one-word answer closes the door, and a long recap asks him to respond to a wall of text he may not have wanted. Pick the one detail that had some life in it: a place you went, something that made you laugh, a small annoyance. Mention that. If you say you went hiking, it rained the whole time, and you ended up eating soup in a diner, he has three things to ask about. If you say it was fine, he has nothing.

Then, if it fits, send the question back in a way that's easy to answer. You don't have to repeat it word for word. Asking what he ended up doing, or whether he got any of the sun that was forecast, gives him a low-effort way to reply. The goal is to make it easy for him to show interest, not to test how much effort he'll put in.

Once you've replied, the ball is in his court, and how long you wait matters more than what you wrote. A few hours is normal for most people on most days. A full day is still fine. If there's no answer after about a day and a half, don't send a message asking why he went quiet, and don't send a second question to fill the silence. Let the thread sit. If he replies later, match the length and energy he used, and keep things moving with a new topic instead of rehashing the weekend.

If the thread goes dead for several days, or he only ever sends short acknowledgements and never asks anything back, that tells you how much he's putting in. You can keep chatting in a relaxed way if he picks it up again, but you don't need to chase. Someone who's interested usually makes some effort to keep the thread alive, even clumsily. When the effort only ever runs one direction, it's time to stop investing in it.