Accuracy of Weather Data

[ahosey01]

Hey guys,

I don't know much about weather - and just moved to a new spot in Wickenburg, Arizona (from Phoenix).  I'm trying to figure out what to expect in the winter.

I was looking up weather averages, and the only meaningful historical data that I can find is from the Desert Research Institute in Reno, which has weather stations all over the southwest (and one about 500 feet from my house).  Here is the location of their station:

 

This is at an elevation of 2070 feet, in the Sonoran desert.  According to their data, we average between 31 and 35 for the low in Dec/Jan - aggregated, the average is 31.9. For our extreme lows, we have dipped into the teens (according to their data) in 19 of the last 30 years.  I can accept that we are colder than phoenix, because we are about 900 feet higher here.  However, there are some other characteristics of this data that make me question its accuracy.

For one, the city of Kingman is 130 miles north of here at 3,400 feet of elevation (in a valley between two 8,000ft+ peaks) and their data shows an average of 5 (36.2) degrees warmer for average Dec/Jan lows.  The data I can find for New River, which is at the same latitude, shows almost 9 degrees warmer in the winter at 2,500 feet of elevation (39.7).  Las Vegas, which is 240 miles north, shows an average of 10 degrees warmer (41.5) at an elevation of 2200 feet on the edge of the city (perimeter of the heat island).

The closest town I can think of in terms of topography, proximity to a river that actually has water, and vegetative cover inside the oasis is Wikieup, which you can see here:

 

 

But according to the DRI data, they have only got below 20 twice in the last 20 years, and average 5 degrees warmer in the winter than Wickenburg (36.4).

This doesn't make any sense to me.  I understand that with the river running through town, the cold air can settle down there.  But why wouldn't the cold air also do that in Kingman, Wikieup or Las Vegas?  Especially when those stations are a.) higher in elevation, b.) more northerly and c.) except for Wikieup, near less vegetation?

Can anyone offer any insight?  Should I doubt the DRI data?

Another interesting point worth mentioning - I have a neighbor (150ft away) with several huge Mexican Fence Post cacti, along with dozens of Aloe plants and an Echinopsis candicans - and he says he has never covered them in the winter or protected any of them.  There are also several CIDP's that look big and healthy growing another 500ft up the road.  My other neighbor has two large Washingtonia filifera with no signs of leaf burn.  I'd think multiple nights per year in the teens would do some kind of damage.  Another neighbor also has a nice citrus tree (I believe it is tangerines but I can't tell for sure).  Wouldn't all these people be losing plants with lows that consistently low?

Edited July 10, 2020 by ahosey01

[Silas_Sancona]

17 minutes ago, ahosey01 said:

Hey guys,

I don't know much about weather - and just moved to a new spot in Wickenburg, Arizona (from Phoenix).  I'm trying to figure out what to expect in the winter.

I was looking up weather averages, and the only meaningful historical data that I can find is from the Desert Research Institute in Reno, which has weather stations all over the southwest (and one about 500 feet from my house).  Here is the location of their station:

 

This is at an elevation of 2070 feet, in the Sonoran desert.  According to their data, we average between 31 and 35 for the low in Dec/Jan - aggregated, the average is 31.9. For our extreme lows, we have dipped into the teens (according to their data) in 19 of the last 30 years.  I can accept that we are colder than phoenix, because we are about 900 feet higher here.  However, there are some other characteristics of this data that make me question its accuracy.

For one, the city of Kingman is 130 miles north of here at 3,400 feet of elevation (in a valley between two 8,000ft+ peaks) and their data shows an average of 5 (36.2) degrees warmer for average Dec/Jan lows.  The data I can find for New River, which is at the same latitude, shows almost 9 degrees warmer in the winter at 2,500 feet of elevation (39.7).  Las Vegas, which is 240 miles north, shows an average of 10 degrees warmer (41.5) at an elevation of 2200 feet on the edge of the city (perimeter of the heat island).

The closest town I can think of in terms of topography, proximity to a river that actually has water, and vegetative cover inside the oasis is Wikieup, which you can see here:

 

 

But according to the DRI data, they have only got below 20 twice in the last 20 years, and average 5 degrees warmer in the winter than Wickenburg (36.4).

This doesn't make any sense to me.  I understand that with the river running through town, the cold air can settle down there.  But why wouldn't the cold air also do that in Kingman, Wikieup or Las Vegas?  Especially when those stations are a.) higher in elevation, b.) more northerly and c.) except for Wikieup, near less vegetation?

Can anyone offer any insight?  Should I doubt the DRI data?

Another interesting point worth mentioning - I have a neighbor (150ft away) with several huge Mexican Fence Post cacti, along with dozens of Aloe plants and an Echinopsis candicans - and he says he has never covered them in the winter or protected any of them.  There are also several CIDP's that look big and healthy growing another 500ft up the road.  My other neighbor has two large Washingtonia filifera with no signs of leaf burn.  I'd think multiple nights per year in the teens would do some kind of damage.  Another neighbor also has a nice citrus tree (I believe it is tangerines but I can't tell for sure).  Wouldn't all these people be losing plants with lows that consistently low?

Always an interesting topic here in AZ..  especially depending on which source for climate info you research..  Never really looked over DRI info..

As far as those "absolute lows", Part of the reason such dips might not do as much damage as they could is because they are typically brief/ occur only a few nights per year, rather than say several days a week each month during the winter.  ..The fact it warms quickly afterwards on most mornings.. Plus our general lack of high humidity / high Dew Points ( Most of the time. Both would contribute to potential frost/freeze damage ) also would limit any damage such an event could do. Even in areas where it snows, it typically melts away quickly the day after it falls, most of the time ..at least in the lower elevation foothill areas that see some every few years..

That said, i too agree that if where your at sees temps below say 19 or 20F a few times per winter 6 out of every 10 years ( would = approx. 19 winters total over a 30 yr timeline.. unless my math is bad, lol ) Imagine, out of the plants you mention, the Citrus would show it.. Could be a hardy variety which can handle those brief cold dips relatively un-damaged though.. Notice any others around town?

Cacti can be variable.. Many Echinopsis/ Trichoceri are said to withstand brief dips into the teens / low 20's w/out much damage ..if dry.. Many Aloes would follow the same basic rule.. Curious which sp. your neighbor might be growing..

Would be interested to see a picture or two of the Mexican Fencepost if/when you get a chance.. They're supposedly hardy to somewhere in the lower 20s.. Some suggest they can withstand down to 19F. It could be the owner of it covers the tips ( most vulnerable part of the plant ) with something like those red Solo Cups on days temperatures are forecast to drop below 30F.. Have seen people do this with various cacti here, and i've yet to see it get cold enough to damage any Cactus grown in yards here. Sun damages more stuff.

 

[ahosey01]

So according to the neighbor, he does not cover, or protect at all, the Mexican Fenceposts.

Do you happen to know anywhere else I could find historic climate data?  In talking to him (keep in mind, he's a little rough around the edges and probably not the most thorough in terms of research and diligence), he told me "The coldest it ever gets is low 20's, and it's definitely colder down here by the river.  That said, I remember once like 30 years ago it got down to 17.  Coldest I've ever seen it by far."  Who knows how accurate that is, but it seemed interesting that he could remember specifically only one time it ever got that cold, when the DRI data seems to indicate that it does that every 6 of 10 years (to your point).

Either way, I'm trying a Bismarckia nobilis, so we'll see how that works out.  It's a deep silver color.

[ahosey01]

Also, I found a few other citrus trees at a local hotel up the road.  I can't tell what kind of citrus they are, though.

[Silas_Sancona]

46 minutes ago, ahosey01 said:

So according to the neighbor, he does not cover, or protect at all, the Mexican Fenceposts.

Do you happen to know anywhere else I could find historic climate data?  In talking to him (keep in mind, he's a little rough around the edges and probably not the most thorough in terms of research and diligence), he told me "The coldest it ever gets is low 20's, and it's definitely colder down here by the river.  That said, I remember once like 30 years ago it got down to 17.  Coldest I've ever seen it by far."  Who knows how accurate that is, but it seemed interesting that he could remember specifically only one time it ever got that cold, when the DRI data seems to indicate that it does that every 6 of 10 years (to your point).

Either way, I'm trying a Bismarckia nobilis, so we'll see how that works out.  It's a deep silver color.

Would definitely try Bismarckia..  Can't see enough of these here. Sabal uresana is another large-canopied, silver colored palm you might add.. Believe @TexasColdHardyPalms is growing a particularly silvery colored " Highland " form which might have even better cold tolerance than the more standard, greenish form ..which is already quite hardy and silver colored as it is. Beautiful Palm regardless.

You could see if the local NWS ( Phoenix ) has historical data for Wickenburg.. would imagine they should.  Not sure how far back any historical data on sites like Accuweather ( personally not a favorite of mine ) and Weather Underground would go.. 

Conversations had with long time residents like your neighbor is also a good step in the right direction..  If his thoughts are accurate, others you talk with should further confirm it, on top of what you observe growing in and around town, and what historical data you can find. Have heard Wickenburg is one of several spots on the northern/western edge of the foothills surrounding Phoenix that appears to be warming a tad faster than Phoenix itself, or other spots in the Southwestern part of the state, particularly during the winter. 

As it stands, the 2012 update of Plant Maps data for AZ has Wickenburg listed as 9a ..but closely surrounded by 9b. I'll bet whenever they decide to do another update, they'll be much more 9b in your area.  I myself trust Plant Map's data more than the USDA's map.  To be Honest, i have lost much more to the heat /sun exposure than to the cold since i moved here.

[TexasColdHardyPalms]

The bizzy we have would handle that without issue. 

[chinandega81]

You can also email directly the NWS Phoenix office and inquire directly. They have responded directly to me before with inquiries. 

 

I would also ask around town, post on other forums asking the same as well and just make observations of yards in the area to see. 
 

On top of that I would go to a local nursery and ask...and just trial by error. Good luck!