The Germans had during Fall Weiss more than 2400 tanks, organized into 6 Pz. Div. Unless the French mobilize preemptively, they will be substantially outnumbered in all categories.
Of these, less than 400 will be PzIII/IV. The French will have better morale and the Germans will still have to cross Belgium to get to the French forces. Or go through Maginot.
Polish campaign was only 10 days shorter, and the Germans weren't exactly running out when it was done. Sure, if the whole things drags on for far more than ~2 months, then you are right. But if that's the case, ammo would be irrelevant anyway, since the German attack would have obviously failed to produce results, and in a battle of attrition, the Heer is bound to lose.
But you are talking of a two front war. The Polish will probably attack from the east and the Germans will need the ammunition there, too. And they were decidedly not swimming in artillery shells or bombs for airplanes. They almost ran out by the end of the Polish campaign. The campaign against the French would require more ammo.
Do they all lock themselves in their refrigerators or someting? By December, things would have long been settled one way or the other.
Come November or December, the coal situation (critical even OTL) would be unbearable. With two front war, movement of troops and military supplies to the East and to the West with limited rolling stock, more coal is left piling up in the mines. Steel production will suffer too. But yeah, you are right they will not freeze instantly. In winter, though...
Does he attack Poland to get there?
That was the idea. I believe they called it Molotov-Ribbentrop pact.