You do understand correctly.
I think my point is that once you've gone past a month or two, the "suckyness" of a nuclear war at least in radiation terms is pretty low. Again, I use Cheyrnobyl as my example. Even though the isotope types and radiation sources are different. Looking at Hiroshima and Nagasaki, the incidence of blast damage, and thermal burn victims is orders of magnitude higher than long term radiation issues on the survivors, just like any other conventional mass bombardment. Granted the yields at the end of WWII were low, around 12-20kt, but American and Russian doctrine moved away from the big multi-megaton bombs as targeting technology improved in the 1970's, and we had less need for "overkill" to compensate for manned bomber losses due to interceptopn.
Now the highest common yields are around 100kt, and if there's any 1-2mt devices, we're likely to use them on each other's missile fields.
I'm just thinking that a brief mention of this, having normal weather, normal plant life, and even having it on the increase would be the most "realistic". People seem to have it ingrained in their collective unconcious from movies, video games etc. that a post nuclear world will be gray, or orange and dusty and desert like for some reason.
It will look like Cheyrnobyl. A burnt blasted area, then wildlife and plants coming back with a vengance shortly thereafter. That's my main point. Also, even in a 100% nuclear exchange, with every nuclear power using their bombs on something/someone, the fires and dust will still be miniscule as compared to just one large volcanic explosion, like Krakatoa, where historical records show it caused just one "failed summer". So IMO, the "nuclear winter" scenario is pretty much bunk as well.
Also, that fallout map you're working from, that's just mainly U.S. military targets. The heaviest red swaths starting in Montana, North Dakota, Kansas etc. are our ballistic missile fields, and SAC bases. Note that Washington D.C., New York, Chicago, and any number of other major cities have not been targeted in that scenario, but most surely would be. If every major military installation, and every city were targeted, plus strategic roadway intersections, and rail yards etc. The map would be meaningless as it would almost ALL be red.
The northwestern U.S. would probably be the only place with some clear patches. They did this so the map would be readable. Which is why certain white supremacist and survivalist groups have preferred the area since the onset of the Cold War.
Honestly, unless a map like this was somehow disseminated during the initial attack or you're a decent meteorologist to make up your own map, you've really got no idea other than "Generally East" which way the U.S. fallout pattern is progressing. It really is the safest thing to hole up for two weeks with no outside trips, and then another month with limited outside exposure before you start moving.