Apple Weather's heatwave predictions probably won't apply to you

AppleInsider

Apple Weather for iOS has come under fire again for a record-breaking temperature prediction that the service maintained for a few hours that seemed unlikely. Here's where the data comes from.

Apple's Weather app on an iPhone

Many iPhone users depend on Apple's Weather app on the iPhone to determine the weather for the day or week ahead. However, while it is highly used and reasonably accurate most of the time, it can sometimes offer questionable forecasts.

The most recent example is from Fresno, California. On Thursday, GVWire reports the Weather app's predictions on Thursday said there would be highs of 121 degrees for July 6 at one point, far above the 115-degree record high set in 1905.

This is in contrast to predictions from the National Weather Service in Hanford, which says the peak should be between 108 and 111 degrees. Later in the afternoon, Apple's forecast updated to a more reasonable 112 degrees for that date.

Meanwhile, the Sacramento Bee says that Thursday morning's predictions for the following week also included hotter than expected temperatures, from 105 degrees on Monday to 110 on Wednesday. For July 6, Sacramento allegedly faced a high of 119 degrees, according to Apple Weather.

While generally accurate enough for most users, the Weather app frequently gets hit by complaints about its predictions. Posts on Apple's support forums have discussed how the app often offers results that differ greatly from other forecasts.

A sourcing issue

It is unknown exactly what caused the unusually high temperature predictions, but it is likely to be a problem associated with Apple's data sources.

Apple's list of data sources on its support pages, shows it uses a number of well-known outlets for its weather data. The sources covering the United States include the National Weather Service/NOAA, The Weather Channel, and BreezoMeter.

While it doesn't collect its own data, instead relying on outside sources, it still does its own processing. Apple gave the Weather app a boost following its acquisition of Dark Sky in 2020, which led to more hyper-local weather prediction features being introduced.

Any in-house algorithms can only be as accurate as the data feeding into it. While it's possible that the sources themselves made a minor mistake, it's doubtful.

The more likely explanation is that the data was corrupted or changed when it was sent to Apple, and it wasn't accounted for, nor was there any sensibility check applied. With the forecast changing within hours, this seems to be a plausible reason for the "correction."

We shouldn't have to say this. Weather forecasting isn't an exact science. AppleInsider recommends that users rely on tools like Apple Weather and any other weather service or application ever made to be a general guide to the day ahead, at least when it comes to forecasts.

Weather predictions are always educated guesses. The further they go into the future, the greater the chance of inaccuracy.

If you are concerned about the results from the Weather app, you can find many other meteorological apps in the App Store.



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dewme

I think that saying “Weather predictions are always educated guesses” undervalues the work that meteorologists, scientists, statisticians, and a whole lot of near and far term modeling experts bring to the table backed by decades of intensive work. It’s not guesswork at all, it’s based on predictive models that have varying degrees of uncertainty associated with them. All predictive models involve uncertainty, just like see with the caches, branch prediction algorithms, speculative execution, etc., in a microprocessor architecture. Data storage caches and browser caches are the same way. Weather modeling and forecasting is very complex fluid dynamics problem and likely consumes a fair amount of the compute time on some of most powerful computers in existence. 

The differences we see around weather predictions have always existed. These differences are attributable to their source and the prediction and probabilistic models behind them. Live data feedback is also part of the models, but even the live data isn’t a controllable feedback loop like it would be in a tunable control loop because the feedback is also extremely variable. Adapting the predictions more often or in real time based on live data, including radar, local weather data collection, visual sightings can help narrow the cone of uncertainty considerably for much smaller prediction time windows. If you’ve experienced a tornado you’ll see the predictions being updated in real time with live feedback and observations because every minute or even seconds matters.

The next time you see a serious tropical storm approaching landfall you’ll see not only the storm path predictions coming from different modeling sources, but also the cones of uncertainty associated with each path prediction. In the end however all of the predictions can be totally whacked because the actual behavior of the storm did not follow any of the predictions.That’s the nature of uncertainty.

Choosing an app for weather prediction should be based on your needs. If you just need to know whether to bring a jacket, umbrella, emergency hydration, bag of sand and a shovel, or sunscreen along you can test drive a few apps and find one that seems to work for you. A lot of these apps use the same sources. On the other hand, if you need an app that can help you deal with an evolving weather emergency in near real time, you’ll definitely need to narrow your search down considerably. The weather app on Apple’s devices, or the weather skill in Amazon’s Echo devices, are generally good enough for most of my daily needs. But when there’s a severe thunderstorm, tornado, or lake effect snow warning in effect, I always go to a weather app that has radar with a wide range of live data overlays, like wind speed and direction, precipitation rates, doppler color coding, lightning strike markers, etc. 

lewval

I find Apple's weather widget to be very inaccurate and just annoying. I live in the desert and the app is always 5-11 degrees less than the official published weather here based on the airport and Accuweather.  On occasion it will indicate it's raining in my area (a rarity) when in fact it's raining in adjacent towns. The app cannot be relied upon. 

shamino

I've also found Apple Weather to be pretty inaccurate.

I much prefer to use AccuWeather, but I don't trust their app - the privacy lists location and usage data as "data used to track you".  I understand that a weather app needs my location, but they don't need to associate it with my account, and they don't need to used it "to track you across apps and websites owned by other companies".  That's just spyware.

So I have a bookmark set to open the AccuWeather web site in Safari, and I get my forecasts from there (relying on an ad blocker to minimize the privacy intrusions).

coolfactor

I don't use Apple's Weather app, mainly because the non-Canadian data sources increase distrust. Instead, my default is the Weather Network, Canada's main weather channel.

It is interesting to compare forecasts across apps. You can definitely see how some lean one way, and others lean another way.

coolfactor

lewval said:

I find Apple's weather widget to be very inaccurate and just annoying. I live in the desert and the app is always 5-11 degrees less than the official published weather here based on the airport and Accuweather.  On occasion it will indicate it's raining in my area (a rarity) when in fact it's raining in adjacent towns. The app cannot be relied upon. 

I dislike how airports are often the default source of weather data, particularly temperature. The geography alone — flat, devoid of vegetation — often results in temperatures far higher than surrounding areas for regions that are very mountainous.

dewme

If you open the weather app on your iPhone (and probably other platforms)  and scroll all the way to the bottom you'll see some tiny type and link. If you click/tap on the link Apple explains where they source the weather data from. Apple's weather app is simply an aggregator, they aren't predicting or forecasting anything themselves. 

I often encounter situations where the weather app is forecasting rain or snow at a certain time for my location and it never happens. But when I look at the radar I can see pockets of rain or snow within the larger geographic region. This is especially true with summer pop-up thunderstorms and especially with winter lake effect snow events that can change rapidly with changes in wind direction and increases and decreases in intensity. 

Bottom line is that that weather forecasts you see in your app may be based on a larger area than your neighborhood, village, city, region, state, or country. Just because the weather app has your location at the top of the screen doesn't mean that the forecast is micro-localized to your actual location. In general I've found that the apps are usually better than TV network weather forecasts because they cover larger areas.

DoctorQ

I’m a fanboi but Apple really messed up Dark Sky.

slow n easy

I stopped using the Apple Weather app for the most part. The rain predictions seem to be very inaccurate. I also hate the NOAA Radar app. I much prefer my local TV channel (WWMT) app paired with MyRadar. Those two together give me much higher confidence on whether or not it will rain.

Dougie.S

DoctorQ said:

I’m a fanboi but Apple really messed up Dark Sky.

Was a great app, and felt much more accurate than the current offering.

entropys

Unrelated kinda, but I find it hilarious when UK weather peoples on the Tv start panicking about a “heatwave” with red colouring on the maps at what looks like above 25°C.
Last week they were all hot and bothered that it might even reach 31°C in some places for a few minutes (88°F). Panic!
In my colonial outpost, Brisbane, 25 is a warmish winter day, and you can easily reach 31°C in early spring or late autumn.  

And yeah, the weather app is consistently higher temp than my calibrated personal weather station, but I put that down to the 9km distance to the official met station, heat island effect and topography. So just allow for it when looking at the Lock Screen when out an about and couldn’t be bothered looking at my PWS app.

hexclock

I find the app is pretty accurate when timing precipitation, but many times the radar doesn’t load properly. When I switch to my local news station website the radar loads as expected. Not sure if that’s a problem with the app or with communication from our local radar station. 

M68000

As good as the  included app is,  it is often incorrect about overnight low temperatures,  sometimes it seems like 10 degrees F difference with reality.

blastdoor

The realistic goal for a weather app is to be right the fraction of times it claims. So for all the times the app says there’s a 70 percent chance of rain, it ought to rain 70 out of 100 times.

I’m not sure if Apple’s weather app is achieving that.