Since March of last year, the amount of time it takes the ForecastWatch system to get and process weather forecasts has been recorded. I was doing some troubleshooting on the web weather forecast retrieval system and as part of that troubleshooting I looked at previous retrieval times.

When I created a graph of the retrieval times, there were a few very large, very curious spikes. Since I was looking at the retrieval and processing times for the public, web forecast component, there could be a number of explanations for the spikes.

They could be a result of problems with the network between ForecastWatch.com's computers and the websites of Accuweather, The Weather Channel, MyForecast, the National Weather Service and the like. If one of the websites was undergoing maintenance, or was having problems, that might also account for the up-tick.

The spikes, where it took longer to retrieve the weather forecasts, could also be because the weather websites were busy. If the web sites were very busy, if a lot of people were trying to access, say Accuweather.com, or Weather.com, it could slow things down for others as their computers become overloaded. If that were the case, they most likely became busy because people were interested in some big weather event affecting or going to affect the United States. On a "normal" weather day, you'd expect a "normal" amount of website visitors. But if something big were happening or expected to happen (a major snowfall or hurricane, for example) people who otherwise wouldn't be visiting, or would only be visiting once, would visit many times. Traffic would go up, and response times would go down.

Here is the graph showing the time it took to retrieve all web-based weather forecasts. These are weather forecasts offered to the public by the weather forecasting companies. ForecastWatch.com also receives non-public forecasts by various means, but their retrieval times aren't included here, since they are not on public web sites.

Click here for a larger version of this graph.

Immediately, you notice four huge spikes: one each on 3/11, 9/19-9/22, 10/20, and 12/5-12/7. All four of those dates can be linked to major weather events affecting a large number of people in the United States.

On 3/11/2005, an Alberta clipper dumped significant snow on New England.

From 9/19 through 9/22, Hurricane Rita was menacing the southern United States. First Florida, and then making land fall early on the 24th on the Texas/Louisiana border.

On 10/20, Hurricane Wilma became the strongest Atlantic hurricane ever recorded, and was heading for land fall near Cancun.

Finally, 12/5 through 12/7 there was a major snowstorm from Washington, DC to Boston.

But there are a couple of major weather events that weren't in the top four.

Notably, Hurricane Katrina didn't have the same web server impact as the some of the other major hurricanes. It could be because of when ForecastWatch pulls web forecasts (the evening). Or maybe after Katrina, people became more interested in future hurricanes because they were unfortunately reminded of their deadly power.