Whither Wi-Fi in Warm Weather?

Caroline Spelman. PHOTO: Reuters/Ueslei Marcelino One would think from reports today that the UK's secretary of state for the environment and rural affairs, MP Caroline Spelman, had lost her bleeding mind. Spelman has been widely quoted about a new report from her agency, Defra, about the threat to infrastructure from global climate change. It covers the extremes of temperature and the routine occurrence of heat above a normal range for the UK, and more storms and severe weather that could ravage Great Britain. The report is an analysis on what changes need be made to keep bridges from buckling in heat or cracking in cold, and nuclear and fossil-fuel plants from suffering damage from previously unthinkable conditions, as well as quotidian issues like floods polluting water supplies and spreading sewage. It's a ripping read, and, please recall, originates from the Tories, the majority conservative part of a coalition government that completely acknowledges the reality of a range of risk potential from climate change. The Conservatives are no Republicans, no matter what else you may say about them. Nonetheless the report's broader issues were overlooked because of a focus on an exceedingly tiny statement buried in it that Spelman highlighted in a speech unveiling the work. Her prepared remarks have her saying:

Our economy is built on effective transport and communications networks and reliable energy and water supplies. But the economy cannot grow if there are repeated power failures, or goods cannot be transported because roads are flooded and railways have buckled, or if intense rainfall or high temperatures disrupt Wi-Fi signals.

The Daily Telegraph paraphrased her as saying in her speech, "The signal from wi-fi cannot travel as far when temperatures increase. Heavy downfalls of rain also affect the ability of the device to capture a signal." The Guardian is more sensible, summarizing her statement as "higher temperatures can reduce the range of wireless communications, rainstorms can impact the reliability of the signal, and drier summers and wetter winters may cause greater subsidence, damaging masts and underground cables." I was puzzled about this, and consulting the report helped a little. First off, the agency isn't talking about Wi-Fi in particular. As is typical, Wi-Fi is used incorrectly as a catchall phrase when "wireless communications" is meant. The report itself says "wireless," and the focus is on large-scale cellular infrastructure using towers (or "masts" as they're called in the UK). Second, the issue of weather affecting signals seems to be tremendously overemphasized in the cabinet secretary's remarks and, naturally, in the coverage. Remember the terrible study and subsequent reporting that alleged Wi-Fi was killing trees all over Europe? So Wi-Fi plus climate change equals headlines. Extreme heat and heavy precipitation may have some affect on signal propagation, but it's likely to be rather small according to a number of geeks I consulted on the topic. The report asserts, "Location/density of wireless masts may become sub-optimal as wireless transmission is dependent on temperature," but I can't find any citations to support that. Rather, the greater risk appears to be from continuously high temperatures causing tower equipment to function more poorly, reducing signal strength, or to be damaged by the heat. Extreme weather could knock out communications by cutting power and backhaul to poles and towers, or toppling them. That's all quite reasonable, and could result in revised standards for how this sort of equipment is deployed, and potentially regulators could change certification standards for telecom gear based on the anticipation of prolonged extreme temperatures. So MP Spelman hasn't gone crazy. But she might get additional consultation before sounding like part of the tin-hat brigade.


  1. Problem? :-)

    Why, it is a well known fact that high temperatures stresses the hardware. Therefore, temperatures above the working limits (~70-100°C) should have an impact on Wireless transmitters as well.

  2. Wi-fi runs on the 2.4 ghz spectrum, the same one that microwave ovens use, and microwave ovens work by exciting water molecules. What’s the air full of when it rains? Or when it’s foggy? The higher the ghz, the more sensitive they are to atmospheric conditions also..

    Lots of other side effects could be considered, for example, warmer temps and more rain mean taller trees, which definitely interfere with radio signals in the ghz range.

    Badly worded, but not wrong in any sense of the word.

    1. Microwaves work by exciting anything with a dipole moment that is placed inside of them. Water, fat, and sugar are part of your more common foods. And the 2.4Ghz frequency isn’t really that special. It’s more likely that it was chosen because it is an open FCC frequency and given how high it is shielding becomes much easier. (In reality a lower frequency would be better as it would allow deeper penetration and more even cooking.)


      Hotter air is able to hold more water vapor, which would lead to more scattering of an electromagnetic signal. Similar issues can be seen when it’s raining, as the rain acts like a moving screen, obscuring the signal.

      1. I’ve noticed problems with most radio signals in the ghz range when the weather conditions are not ideal, I just used the wi-fi microwave example because it’s an easy way to relate the idea.

    2. There’s some effect from rain. It’s like going through trees or people. You’re more likely to see attenuation of signal from a poorly connected cable or one that’s badly terminated.

      I know people who’ve designed public and large-venue Wi-Fi systems, including Coachella, where they’ve had 100 degree weather in April. They don’t consider temperature when they design the layout of the site. .1 Watt radios with a range of 100 yards aren’t going to need network redesigns for a half-decibel drop-off.

      This is, as Glenn says, not about Wi-Fi

  3. Anecdotally, I’ve encountered the problems of weather interfering with wireless internet. I live in rural Canada and my only option for speeds better than dial-up is to go with a wireless provider. When it’s raining or extremely humid I generally notice a severe slow-down of my bandwidth, and sometimes I’m cut off entirely.

    I understand there seems to be some overstatement of the impact the climate may have on wireless. I can only surmise that the MP is trying to draw more attention to the problems of climate change by dropping a term that will be recognized by a wider range of people?

  4. Good article. But while the Conservatives may be no republicans, they are far from environmentalists. While their rhetoric has been green their actions are more a dirty brown – they’ve gutted key green targets like the aim to build a million zero-carbon homes and have scrapped the Sustainable Development Commission which was meant to hold the government to account on green issues.

    For more on this take a look at: http://www.foe.co.uk/news/greenest_government_ever__30665.html

  5. More of a question than something that I’m certain of: given the absorption and scattering of 2.4 GHz microwave radiation by water molecules, and given that warmer air can contain more moisture, is the increased amount of water in hot saturated air significant enough to degrade communications? Once again, its not the heat as much as the humidity.

  6. Even the actual reports are pretty vague, but I’m pretty sure that most of the actual concern is over cell phone networks. The one mention of WiFi seems to be a reference to a WiFi network on a National Rail line, which was damaged by a freak ice storm.

  7. Am I the only one who is perhaps a tad sceptical regarding this? I have worked in telecoms in some of the most extreme locations in the world and have not experienced significant outages when temperatures have been >50C and humidity levels so high that waving your hand through the air leaves it dripping OR doing the same results in a risk of frost bite. The issue is one of what is ‘normal’ and building systems that are able to cope with the abnormal. With the UK, the overall infrastructure (like the US is experiencing) has had little investment in upgrading or maintaining it. A chiller system that has worked efficiently without failure for a lengthy period WILL fail if it is suddenly having to jack up its power usage and operational ‘on’ time. Were the systems built properly in the first place, most of these failures would not happen. The US is one place I anticipate there will (sadly) be some significant failures – bridges, power grid etc – due to zero or poor maintenance.

    One particular US problem that I have never come to terms with is the power lines being above ground on poles. Particularly in areas prone to ice storms. The cost of outages and the need to rebuild are significant. Why not put them underground where other countries do this?

    1. @HotPepperMan: Why skeptical? The report is saying the same as you. Infrastructure built for one climate can fail badly when exposed to a different climate. Looks like many countries are going to have to learn this the hard way.

    2. I live in a place where it’s 40°C to 50°C all summer, and electronics go belly up very quickly. Battery life, in particular, is a fraction of what it is in less extreme climes. Non-electronics, like houses and roads, don’t fare very well either.

      God created Palm Springs to train the faithful.

  8. Maybe this is just an excuse, I think that while she does not like your wi-fi technology is disconnected, you can create a new better technology that can penetrate the rain or needs it for transportation, I think the world of technologies, there is still much to be discovered and that there are still bigger and more powerful technologies to discover and I would like to join one of these desubrimientos revolutionaries.

  9. Maybe this is just an excuse, I think that while she does not like your wi-fi technology is disconnected, you can create a new better technology that can penetrate the rain or needs it for transportation, I think the world of technologies, there is still much to be discovered and that there are still bigger and more powerful technologies to discover and I would like to join one of these desubrimientos revolutionaries.

  10. My WIFI is much less reliable in heat and rain. Heat because the router hardware overheats. Rain most likely because of the 2.4 ghz issue (it seems to work a bit better at 5 ghz, but that could just be new hardware). Also on the moisture issue, I have had computer hardware ruined by humidity–just try explaining how the inside of your laptop rusted to some “genius.” Those of us who live in the center of a continental mass, what I call the “intemperate zone,” have learned to deal with it–mostly through ubiquitous air conditioning, something many Europeans have never felt the need for previously.

  11. In the VHF and UHF radio ranges (the 2.4 GHz frequency band used by many WiFi devices is in the upper UHF) there’s a type of long distance propagation called tropospheric propagation, which is weather-dependent. In hot, humid weather VHF & UHF signals can propagate very long distances, especially along weather fronts. I suppose it would be possible for this to happen to WiFi signals, which would increase the interference your WiFi network would experience, with a consequent degradation in its performance.

  12. One way or the other, this article tried to make a “the Internets” meme, and to put Caroline Stelman as a fool, and failed in grand.

    1. Actually, this is critiquing Spelman’s sloppy explanation and credulous media accounts. No memes need apply.

  13. Does anyone know what plant species that is in the pic there?

    It’s beautiful and I wish to grow this at my home.

    1. It appears to be a fascinator that escaped the royal wedding and got stuck to an asparagus spear.

  14. Anyone who doubts the effect of humidity (in particular, fog) on WiFi has never lived in San Francisco and stolen service from a neighbor…

  15. I am an Extra Class Ham radio operator.
    I am licensed by the FCC to build and operate high powered radios on the 2.4ghz ham frequencies (and all other ham freqs).

    This article is beyond ludicrous. Its outright propaganda and BB should be ashamed for running it.

  16. This should really read about how Spelman and colleagues sold the English public down the river over our publically owned national woodland and forests. How she received a resounding ‘No’ from the public about the blatant sell off of our national woodland heritage and admitted that a rethink was in order, only to then do a complete u-turn a couple of months later! Welcome to UK PLC where even our natural heritage is for sale to the highest bidder. She and her contemporaries say they care about our environment in the shadow of global warming with this report in one hand, but then try to flog our dwindling natural landscape to the highest bidder with the other.

    A few hundred years ago you could walk the entire length of the British Isles from Lands End to John O’Groats and not break tree cover. Now, we have only 12% cover thanks to rampant deforestation, out of control suburbanisation and unchecked development. By comparison, France has 29% cover and Germany 32%.


    She should pull her finger out and stop producing sketchy reports about what might happen and start looking at positive reforestation that will not only soak up man made CO2 but also mend the mess caused by previous generations to our landscape.

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