Now that spring has begun on all calendars (meteorological spring started March 1) one would expect temperatures in the 60s, and that looks like what we will have through the weekend. A cold front just off the northern California coastline will stall out before reaching us, but will allow more cloudiness to come through. Look for temperatures to top out in the 60s Saturday and Sunday, before a slightly stronger system comes through on Monday, giving us a slight chance of showers.
A reader made the following comment: “From what I’ve seen, your weather reports always mention how far each day’s high and low temperature deviates from average. I’m fairly certain those averages are reset every ten years. Have you ever considered comparing today’s averages to what they were back in the ’90s or ’80s? You may not be looking to do more than report on the current conditions, but showing people the amount these averages have probably increased over the last 20+ years could open their eyes to how global warming is affecting their daily lives.”
Actually the average temperature for the Reno area (and all National Weather Service stations) is calculated using a rolling 30 year average, which is recalculated every 10 years. But there’s a problem trying to use Reno’s temperature for gaining any perspective on the world’s climate. The vast majority of the apparent warming we are seeing here in Reno has to do with urban heat island effect, as opposed to any global effect. For instance, 30 years ago, the airport (the official reporting station for Reno) was surrounded by irrigated alfalfa fields. Now it’s surrounded by concrete.
In fact, the problem has been made even worse by the movement of the weather station from well off the runways, to the southern end of the runway (in the early 90s), and then to it’s present position farther north, right in the middle of the two runways.
This all has had a very dramatic effect of the temperatures… especially the overnight lows. Even the largest estimates of global warming have our global average temperature rising less than 1 degree C in the last century. (That may or may not be a significant number, but that’s for another discussion.) Urban heat island effect here in Reno has probably raised our mean observed temperature by several times that. That’s why that rolling average is used.
So in theory, a record high temp in the 1960s is actually more impressive than a record high temp today. I like this article. It makes a person think how much has changed the last hundred years is just a drop in the bucket compared to thousand of years ago, weather speaking.
Mike Alger said:
Aaron…to a certain extent what you say is true…although the urban heat island effect that we see so much here in Reno affects the overnight low temperatures more than it does the daytime highs. But even so it does have an effect on the highs.
Mike Alger said:
Oh without a doubt. If becomes even more apparent just moving away from the airport. I often ride a motorcycle to and from the TV station, located right next to the Reno-Tahoe Intl Airport. Just driving a mile to the south of the runway, you can feel a very significant cooling over the space of a hundred yards or so…kind of like hitting a cold brick wall. There’s no change in elevation…just the surrounding ground cover.
Great article, really informative! 🙂
Dana Trimble said:
The heat island is also very apparent if you look at the overnight low temperatures in the surrounding areas such as Cold Springs or north Spanish Springs where the temperature is typically 10-12 degrees F cooler (on a clear night) than the Reno low temperature.