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Garmin connect temp readings - Accurate?

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Garmin connect temp readings - Accurate?

Old 08-16-21, 10:11 AM
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Ogsarg
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Garmin connect temp readings - Accurate?

Yesterday I rode into a remote area where there was either no cell service or 1X (no data). This is south of where I live and it's always hotter in that area. It was cooler than usual when I left my house but got progressively hotter as I went on. I was on a road with rolling hills and a gradual incline that climbed a little over 2k over 15 miles with the steepest grades in the 8-10% range. I knew it was hot but wasn't sure how hot. I drank both my 24oz bottles (one with electrolyte solution) before heading back. It was 15 miles to a small country store and by the time I got there, I needed water desperately. Bought a 48oz bottle and drank half of it and put the other half in one of my empty bottles, which I drank on the way home. Total ride length was 56 miles.

Looking at the ride details on the Garmin Connect app, it said the average temp was 95 with the max temp of 108, both sound quite a bit high to me. I have a Garmin 530, which I understand does not have a temp sensor so wondering how useful it is.

What has been your experience with the temp data? Have you found it to be accurate?
Where does the data come from?
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Old 08-16-21, 10:25 AM
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So what are you doing with the data that you need more accuracy?

The Edge 530 does have a temp sensor in it's internals and you can display that value on your pages. And it's in the data that you upload. However since it's on the circuit board with the GPS and other stuff it's not overly responsive to temperature changes. I just rode a 14'er that was 46F at the top, but 63 at the bottom. My Edge 530 just shows 50F for most all the ride down. What will I do with that info if I had more accurate info?

If you are talking about the local weather reports that Garmin Connect gives you.... well like any weather report they are only accurate for the exact location they were taken from. So unless you want to ride in circles around that weather reporting station, you have to allow for some inaccuracy.
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Old 08-16-21, 10:31 AM
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I think I've found it fairly accurate on my 520 anyway. The device I am pretty sure has its own temp sensor (https://www8.garmin.com/manuals/webh...4E152178F.html ), but maybe in Garmin Connect it's providing the 'heat acclimitization" temperature which accounts for humidity etc from weather data provided by nearby weather stations. Kinda sounds like a 'real feel' type of reading. Have you tried looking at the data from your ride in another app?
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Old 08-16-21, 11:06 AM
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Originally Posted by Ogsarg View Post
Yesterday I rode into a remote area where there was either no cell service or 1X (no data). This is south of where I live and it's always hotter in that area. It was cooler than usual when I left my house but got progressively hotter as I went on. I was on a road with rolling hills and a gradual incline that climbed a little over 2k over 15 miles with the steepest grades in the 8-10% range. I knew it was hot but wasn't sure how hot. I drank both my 24oz bottles (one with electrolyte solution) before heading back. It was 15 miles to a small country store and by the time I got there, I needed water desperately. Bought a 48oz bottle and drank half of it and put the other half in one of my empty bottles, which I drank on the way home. Total ride length was 56 miles.

Looking at the ride details on the Garmin Connect app, it said the average temp was 95 with the max temp of 108, both sound quite a bit high to me. I have a Garmin 530, which I understand does not have a temp sensor so wondering how useful it is.

What has been your experience with the temp data? Have you found it to be accurate?
Where does the data come from?
The old woman has a 530 edge and the temp varies 3-5 degrees depending if the GPS is on so it must have its own sensor. Same with my 520 and our temps rarely agree. The 530 is usually 4 deg hotter.
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Old 08-16-21, 12:06 PM
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My 530 is way more accurate on cloudy days or on early rides before the sun is up - in other words, the sensor is sensitive to heating of the device itself whether from the electronics or the sun. That said, I do enjoy glancing at the temp. Not sure why given that I know it often reads high.
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Old 08-16-21, 02:37 PM
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Originally Posted by ericcox View Post
My 530 is way more accurate on cloudy days or on early rides before the sun is up - in other words, the sensor is sensitive to heating of the device itself whether from the electronics or the sun. That said, I do enjoy glancing at the temp. Not sure why given that I know it often reads high.
^This.

Data from yesterday's ride shows that I left the house when it was around 86 F, but the "feels like" temperature outside was 97 F. Just after noon, when the sun's highest in the sky and the incident angle of the sun's rays are most acute in relation to my 530, sensed temperatures spiked to 108 F. Given there's an internal temp sensor on the 530 and the screen has a black bezel, I'm not surprised that the unit reads higher than what a weather forecast might predict.
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Old 08-16-21, 02:42 PM
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Originally Posted by Sy Reene View Post
I think I've found it fairly accurate on my 520 anyway. The device I am pretty sure has its own temp sensor (https://www8.garmin.com/manuals/webh...4E152178F.html ), but maybe in Garmin Connect it's providing the 'heat acclimitization" temperature which accounts for humidity etc from weather data provided by nearby weather stations. Kinda sounds like a 'real feel' type of reading. Have you tried looking at the data from your ride in another app?
Heat acclimation is when Garmin tries to guess how adjusted you are to the heat. Imagine somebody from Alaska visiting Texas for a race, they would want a few days to get used to the temperature and not just for jet lag. It doesn't look at factors like wind and humidity for how stressful the heat felt, and they show it separately from the ride data because it's about you not about that activity.
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Old 08-16-21, 03:35 PM
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Thanks for all the feedback. The specs for the 530 I saw online don't list a temperature sensor so assumed it did not have one. I also noted in the link posted above that being in full sun will cause a higher than actual reading, which makes sense if it has an internal sensor.

Just to clarify, I am not using the reading for any specific purpose and don't have it included in the display. Was just surprised to see the readings when reviewing the stats of the ride so was curious as to what I really subjected myself to, heat wise. My best guess is that both average and max are 10-12 degrees higher than actual.
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Old 08-16-21, 03:38 PM
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When you save an activity Garmin looks up a weather service and displays that on the map. It's only one temperature for one point in time. If you're getting a history (with a graph if you scroll down) it means you recorded that data yourself.
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Old 08-16-21, 07:20 PM
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Originally Posted by Seattle Forrest View Post
Heat acclimation is when Garmin tries to guess how adjusted you are to the heat. Imagine somebody from Alaska visiting Texas for a race, they would want a few days to get used to the temperature and not just for jet lag. It doesn't look at factors like wind and humidity for how stressful the heat felt, and they show it separately from the ride data because it's about you not about that activity.
Good info. Thanks. I don't typically look at my ride data in Connect so wasn't sure exactly how temperature is represented in a post ride presentation; I usually look at Strava -- to your other point, yeah I'd be looking at the temperature graph in Strava 'analysis' tool.
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Old 08-17-21, 09:17 AM
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I've always felt that Garmin buys printed circuit boards off the shelf from other manufactures that mass produce them for many different uses in a variety of products. I'd be surprised if the actual board and components themselves are Garmin proprietary designed but I might well be wrong. And even if the PCB is Garmin's, the chip on the board that contains the baro sensor and temp sensor is likely not Garmin's proprietary chip.

The temp sensor on the PCB or chip is probably there for those devices that need to have the barometric sensor calibrated for temp too. Though previously Garmin has said they do not compensate the barometric sensor for temperature. However that statement doesn't exclude the possibility that the boards circuitry might use that temp sensor to adjust the barometric sensor before Garmin's software even gets the elevation data.

Being buried on the PCB well inside the case, I've always found the temp readings too slow to react to rapidly changing temps I ride through.

Last edited by Iride01; 08-17-21 at 09:23 AM.
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Old 08-19-21, 07:34 PM
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I always thought it was high but then I realized that it WAS much hotter than the air temperature near the ground. As the asphalt heats up, it get hotter and hotter near the ground. So my 90 degree ride will start out there and after a few hours, it absolutely feels much hotter and can hit 100+ near the ground. I always thought it was way too high till recently.
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Old 08-19-21, 08:57 PM
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Originally Posted by Iride01 View Post
it's not overly responsive to temperature changes.
This is true. I find if I have my 530 in my den charging over night and go out on a cool morning, My ride is in the 70s for many miles according to what I see after my ride uploads. I was disappointed for a couple of seconds and then I decided I don't really do anything with the information from my cadence and heart rate sensors which are more important so I had a beer instead of worrying about anything.
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Old 08-19-21, 09:11 PM
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Originally Posted by Chuck M View Post
This is true. I find if I have my 530 in my den charging over night and go out on a cool morning, My ride is in the 70s for many miles according to what I see after my ride uploads. I was disappointed for a couple of seconds and then I decided I don't really do anything with the information from my cadence and heart rate sensors which are more important so I had a beer instead of worrying about anything.
​​​​​​For anybody reading or who finds this thread later through google: this is the correct answer.

Temp data is for bragging rights, wrt rule 5 (HTFU) and not really useful beyond that in the moment.
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Old 08-21-21, 10:03 AM
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Originally Posted by Seattle Forrest View Post
​​​​​​For anybody reading or who finds this thread later through google: this is the correct answer.

Temp data is for bragging rights, wrt rule 5 (HTFU) and not really useful beyond that in the moment.
I guess you don't ride in hot weather. We have to watch it when it gets over 95 for a period of days. There are consequences.
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Old 08-21-21, 10:18 AM
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Originally Posted by popeye View Post
I guess you don't ride in hot weather. We have to watch it when it gets over 95 for a period of days. There are consequences.
That seems like a stretch to make that assumption about someone.

I don't use my Garmin device to determine if it's too hot for me to ride, I go outside and see what it feels like and listen to or look up the weather reports and forecasts. As well look at the weather radar for my area.

Any one that put faith in their gps device for telling them the temps and whether I'd have to think must be desperately lacking other sources of obtaining information.
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Old 08-21-21, 11:02 AM
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I have never seen a properly calibrated or accurate thermometer, barometer, or altimeter in a small device.

Last edited by MoAlpha; 08-21-21 at 04:00 PM.
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Old 08-21-21, 11:57 AM
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Originally Posted by Iride01 View Post
That seems like a stretch to make that assumption about someone.

I don't use my Garmin device to determine if it's too hot for me to ride, I go outside and see what it feels like and listen to or look up the weather reports and forecasts. As well look at the weather radar for my area.

Any one that put faith in their gps device for telling them the temps and whether I'd have to think must be desperately lacking other sources of obtaining information.
Now you're making assumptions. First off I don't even use the GPS. I have a pro level weather station that reports to Weather Underground and my web page. We ride 25mi. inland 5 days a week from the beach to Santa Ana Canyon which is in an entirely different weather system. I check WxUnderground stations every day all the way out so I can be prepared. I know how the Garmin relates to local stations when I'm out in the sun (weather stations report shade) on hot asphalt and in the canyon it can be well over a hundred. A load of 250mi/week and too many days over 95 can really set you back.
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Old 08-21-21, 12:00 PM
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Originally Posted by popeye View Post
I guess you don't ride in hot weather. We have to watch it when it gets over 95 for a period of days. There are consequences.
I was riding up a hill on the hottest day in history here at 111* F, so yeah, no idea what I'm talking about. I prefer to swim on days like that but was expecting company and didn't have time.

Once you get on the bike and leave, you've already made the relevant choices and knowing what temperature it is but being delayed 45 seconds in that knowledge shouldn't have consequences. The weather forecast is pretty good these days.
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Old 08-23-21, 07:51 PM
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Many Garmins have an issue with heat soak causing the temperature to read a lot higher than ambient air temps. This is especially true if the unit is just sitting in the sun, like at a rest stop or whatever. My 520 will read a bit higher than actual if it’s in the sun while riding. It will be way high if it sits in the sun motionless.
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