We need a weather forecast map mode for the next 1-2 weeks. Accuracy should be tied to tech.
This way a player can decide to invest tech slots into weather forecast or not.
For major offensives like Barbarossa or naval invasions like D-Day, it makes a huge difference to set the start date when you expect to have 1-2 weeks good weather.
With the system we have now, you only see the weather at this very moment and it can change in an instance.
That level of weather forecasting just wasn't reliably available in this period. Obviously there are parts of the world where even the village idiot would get it right. (IBurma, Ceylon, and India are tolerably dry for months, then they are very hot for months, then the monsoon comes and it poures for months. Peking was very cold and very dry for almost the whole of winter. And so on.) Players should be able to make those guesses themselves.§ But the task was much more difficult in the parts of the world where the weather is changeable (western Europe and East Asia during the plum rains). As the British D-Day meteorologist Charles Douglas
told his American colleagues: "a forecast for more than a day or two ahead in this country can be nothing more than speculation." The Allies had the benefit of an extensive network of weather stations (particularly in the Atlantic, which dictates the weather for western Europe), but they didn't have satellites and they didn't even have the peacetime level of reports from shipping, since radio silence was essential. And all sides were calculating everything by hand (and to a large extent estimating by eye), so they couldn't take full advantage of the data they did have. Long-range forecasts were made but were far less reliable than today. Even the next day forecasts were far worse than now. One reason the Germans were unprepared for D-Day was that they didn't expect 6 June to have acceptable weather. If the invasion hadn't happened on 5-7 June, then the next window was 18-20 June. The Allied forecast produced on 17 June predicted excellent weather, so an invasion would have gone ahead, but the 18-19 June actually had a terrible storm that would made a successful invasion near-impossible.
Given that the weather could only really be forecast a day or so ahead, players just wouldn't have time to make major changes. I would like a precipitation map, but I think the current day's report is fine..
§ And the AI could be scripted to know that kind of predictable weather, but I don't know whether it takes weather into account at all. It barely knows rivers exist, never mind rainstorms.