# Do highways and/or rivers affect weather?
**URL:** https://boards.straightdope.com/t/do-highways-and-or-rivers-affect-weather/999209
**Category:** In My Humble Opinion
**Created:** [March 22, 2024, 4:45pm UTC](https://boards.straightdope.com/t/do-highways-and-or-rivers-affect-weather/999209 "2024-03-22T16:45:15Z")
**Posts on this page:** 3
**Page:** 2
### Author:  [@Dinsdale](https://boards.straightdope.com/u/Dinsdale)
#### Post date: [March 29, 2024, 4:53pm UTC](https://boards.straightdope.com/t/do-highways-and-or-rivers-affect-weather/999209/21 "2024-03-29T16:53:56Z")
Heading east towards Chicago on certain winter mornings, the bank of clouds over the lake almost look like a mountain range, with clear blue sky above them and to the west. Pretty neat.
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### Author:  [@TriPolar](https://boards.straightdope.com/u/TriPolar)
#### Post date: [March 29, 2024, 5:05pm UTC](https://boards.straightdope.com/t/do-highways-and-or-rivers-affect-weather/999209/22 "2024-03-29T17:05:32Z")
I95 and it’s location that follows the low coastal areas up the east coast is another case of easy identification. It is rather remarkable, I live barely a mile west of 95 and the change across the highway is very noticeable but we are right where the terrain in rising.
Narragansett Bay certainly makes a difference though. It tends to split a nor’easter passing over it. It’s quite clear on a radar map with snow storms. My house is about 10 miles due north of the bay and we’ve been saved from heavy snow that came down just a couple of miles to the east, west, and north.
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### Author:  [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)
#### Post date: [March 29, 2024, 5:13pm UTC](https://boards.straightdope.com/t/do-highways-and-or-rivers-affect-weather/999209/23 "2024-03-29T17:13:14Z")
> [@Dinsdale](#):
>
> I’m quite confident that roads are too small to effect weather, and would wager the same holds true for rivers. Around Chicago, they often talk about weather differing north and south of I80, and east or west of I 65 in Indiana. But those roads just delineate the lake effect of Lake Michigan, depending on whether the wind is westerly or northerly.
> [@Dinsdale](#):
>
> A very quick google “Do roads affect weather” yields many results saying roads are used by meteorologists simply as a convenient descriptor.
Speaking as an amateur meteorologist, and Chicago-area resident, I think that this is absolutely what’s going on. Roads and rivers are just too small, in the grand scheme, to have any appreciable effect on the weather, or to serve – in and of themselves – as a “dividing line” between two different weather conditions.
But, valleys (which rivers, and some roads, tend to follow) _can_ have some effect, as others have said. And, roads and rivers _can_ happen to serve as easy-to visualize markers for the boundary line between two different microclimates. For example, as @Dinsdale notes, Interstate 65 in northwest Indiana is often used by meteorologists to define, for the public, the rough dividing line where significant lake-effect snow is predicted to fall. This has **nothing** to do with any impact of I-65 itself, and more that it’s a rough marker for where wind out of the northwest will have had enough distance traveling over Lake Michigan to generate snow: if you’re substantially west of I-65, lake effect snow is pretty uncommon, whereas if you are on or east of I-65, you frequently get dumped on by snow.
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