UHI In Las Cruces, New Mexico

There are some interesting things folks should know about Las Cruces in terms of urban heat island effect (UHI). First of all, it's in the desert southwest. Temperature extremes between daytime and night are far more extreme than coastal city dwellers can usually imagine. Seventy F during the day and twenty at night is not unusual ten miles outside of town. In town it might only be a spread of seventy-thirty, but still it's pretty extreme. Not at all unusual to desert dwellers. We ALL know the concrete in town is where the heat remains. Sand does not retain heat well at all at night. Concrete does. So the UHI effect is greater around desert cities. Las Cruces has other interesting things to keep in mind. First, it is in a river valley. That tends to concentrate cold near the area indicated on the map, because it is closer to the river, hence lower elevation. Unless an inversion is in effect, which reverses it. Second, the "river" in the valley is actually dammed up-stream during the winter time, so there is no heat flowing into or out of the valley as is usual in other river valleys. Third, there are agricultural pockets of trees, mainly pecans, but also some pistachios that are grown in the area which can change temperatures dramatically in the valley from street to street, and decade to decade, depending on the planting patterns of certain crops in the area. The effect of the trees is incredible during the summertime, although I don't know how irrigation is handled during the wintertime. All I know is you can experience pockets of temperature variations of fifteen degrees, depending on which orchard or field you happen to be driving by.

I don't know where the official temperature is recorded for Las Cruces, but airports are the usual temperature reading locations in desert locals that I've seen, and the airport for Las Cruces is outside of town, up on the mesa, not in the valley where the map indicates the UHI. I will say this though... any temperature readings around desert cities are full-on crap in terms of historical accuracy. The UHI effects are huge. If you watch weather patterns around El Paso, just forty miles south of Las Cruces, you will often see precipitation evaporate on the radar as it approaches the city. It's like a magical dome of protection. The temperature for El Paso used to be recorded nearer to downtown at the international airport, but I believe is now recorded fifteen miles west of town on the mesa at the NWS station... STILL not far enough away to not be affected by the massive UHI there. And, keep in mind, the cities have experienced explosive population growth over the last twenty years.

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