alt Hacker NewsData is released every minute, every five minutes, every hour, and then 6 hour high/low, and then mid-day preliminary reports, so there is no last-minute since any one of those reports could contain data (with various validation/rounding caveats) that could eliminate a market of temperatures, so there isn't really a last minute.
My conclusion was to focus on forecast and attempt to predict the temperature better than forecast vs. market implied probability rather than attempt to respond very quickly to published information. I learned (with my skills) the latter was a losing proposition, but the former isn't impossible (although also possibly beyond my skills it seems).
A lot of people assume insider trading in weather markets on data that's publicly available but they're unaware of.
It's also a massive whoosh that you only consider the insider trader aspect in choosing to play weather markets. No consideration of how you would get an edge in these markets against extremely powerful weather models used by meteorologists who understand the subject and how to apply the data. It seems much different than betting against political pundits.
It's also another whoosh not realizing that some of these stations are actually not that secure when you take a look at them in real life. Less insiders than betting on things that aren't tamper-resistant.
Also, a lot of people complain about insiders profiting from last minute data. One way to limit this would be requiring markets to close in advance of final data, but people love to gamble (read: bet without an edge) on things at the last minute across all prediction market subjects.