<p>Based on the <code>maximum air temperature Time series plot</code> plot below. What could be a possible reason(s) for <code>Maximum Temperature</code> to decrease over time, even though <code>minimum and mean</code> temperatures are increasing? And actually, I only this behavior in the some months not all of them which is also interesting.</p>
<p>Someone did tell me that <code>Maximum temperature</code> tends to show this behavior in a timeseries, but didn't tell me why.</p>
<p>The area is a coastal region in North America and the data was collected from the PRISM model.</p>
<p><a href="https://i.sstatic.net/ASFCF.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/ASFCF.png" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2022-07-21T17:22:46.783Z
What is the source of the graph?
Fred
CC BY-SA 4.0
2022-07-21T17:32:59.123Z
@Fred, `R` linear model regression.
Ed_Gravy
CC BY-SA 4.0
2022-07-21T18:14:47.150Z
Do you see this trend over larger datasets... 40 years in one specific month?  One could say it has more data in it than 41 years as it is separate locations, but it's clear from your graph that values for the year have limited independence from each other?  A regression slope on such a limited period will tend to be driven heavily by one or two outliers (as it looks like 1986, 2012, and even 2021 a bit were?)
JeopardyTempest
CC BY-SA 4.0
2022-07-21T18:15:09.323Z
@JeopardyTempest, I did mention that I got the data from the PRISM model.
Ed_Gravy
CC BY-SA 4.0
2022-07-21T18:16:14.313Z
@JeopardyTempest, sorry for the confusion, these are monthly average values spatial distributed. So that's why each year has multiple values.
Ed_Gravy
CC BY-SA 4.0
2022-07-21T18:18:19.797Z
@JeopardyTempest, yeah I don't know someone on `stat.stackexchange` advised me against analyzing `maximum air temperature` change due to this trend behavior (so I guessed it's a common occurrence). But, he did not tell me why.
Ed_Gravy
CC BY-SA 4.0
2022-07-21T18:21:59.553Z
@JeopardyTempest, what's even more interesting is that in general, I observed that in case of my dataset `minimum and mean temperature` increased in areas close to the coast and were lower in the inland areas with dense vegetation away from residential areas (which makes sense). However, it's the opposite for `maximum temperature's` spatial trend. But anyways that a different question, but just wanted to share.
Ed_Gravy
CC BY-SA 4.0
2022-07-21T18:23:45.543Z
I've never used R... but believe the linear regression statistics (R^2, P values) may be useful in analyzing the strength of the regression and important to someone's answer... looks like [this site](https://www.learnbymarketing.com/tutorials/explaining-the-lm-summary-in-r/) has input on how to get those things.
JeopardyTempest
CC BY-SA 4.0
2022-07-21T18:26:29.257Z
@JeopardyTempest, thank you, yes in most months the `p-value` is `>` `0.05` so statistically speaking this behavior is by chance. But, I was wondering if any other climatological variables might be the cause.
Ed_Gravy
<climate-change><temperature><climatology><air>
Maximum Air Temperature Decrease Over Time
Ed_Gravy
# Maximum Air Temperature Decrease Over Time

(Asked by: username_0 on 2022-07-21)

Based on the `maximum air temperature Time series plot` plot below. What could be a possible reason(s) for `Maximum Temperature` to decrease over time, even though `minimum and mean` temperatures are increasing? And actually, I only this behavior in the some months not all of them which is also interesting.

Someone did tell me that `Maximum temperature` tends to show this behavior in a timeseries, but didn't tell me why.

The area is a coastal region in North America and the data was collected from the PRISM model.

[![enter image description here](https://i.sstatic.net/ASFCF.png)](https://i.sstatic.net/ASFCF.png)

**Tags:** climate-change, temperature, climatology, air

> **Comments:**
> **username_1**: What is the source of the graph?  
> **username_0**: @username_1, `R` linear model regression.  
> **username_2**: Do you see this trend over larger datasets... 40 years in one specific month?  One could say it has more data in it than 41 years as it is separate locations, but it's clear from your graph that values for the year have limited independence from each other?  A regression slope on such a limited period will tend to be driven heavily by one or two outliers (as it looks like 1986, 2012, and even 2021 a bit were?)  
> **username_0**: @username_2, I did mention that I got the data from the PRISM model.  
> **username_0**: @username_2, sorry for the confusion, these are monthly average values spatial distributed. So that's why each year has multiple values.  
> **username_0**: @username_2, yeah I don't know someone on `stat.stackexchange` advised me against analyzing `maximum air temperature` change due to this trend behavior (so I guessed it's a common occurrence). But, he did not tell me why.  
> **username_0**: @username_2, what's even more interesting is that in general, I observed that in case of my dataset `minimum and mean temperature` increased in areas close to the coast and were lower in the inland areas with dense vegetation away from residential areas (which makes sense). However, it's the opposite for `maximum temperature's` spatial trend. But anyways that a different question, but just wanted to share.  
> **username_2**: I've never used R... but believe the linear regression statistics (R^2, P values) may be useful in analyzing the strength of the regression and important to someone's answer... looks like [this site](https://www.learnbymarketing.com/tutorials/explaining-the-lm-summary-in-r/) has input on how to get those things.  
> **username_0**: @username_2, thank you, yes in most months the `p-value` is `>` `0.05` so statistically speaking this behavior is by chance. But, I was wondering if any other climatological variables might be the cause.  

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## 0 answers

