If this is happening when it's merely cloudy, and not even raining, report it to your dealer, and insist they call TechLine. It not being a sunny day should not obstruct the radar. I had the same issue, and TechLine didn't have any outstanding reports about it. I think the radar programming needs re-calibration, but Honda isn't going to do anything unless people report it.
The dealer didn't actually fix anything, but they said they would try a re-aim if I reported it a second time.