Episode Details

Today’s Podcast

We interview climate scientist Daniel Swain, who, besides being a University of California Ag and Natural Resources employee at the California Institute for Water Resources, is well known on social media. Swain runs the Weather West website as well as his frequent presentations talking about extreme weather conditions in California and the west on YouTube, Bluesky, and other social media outlets.

TIPS FOR SETTING UP A HOME WEATHER STATION

One common topic when two gardeners meet: the weather. Gardeners are usually grousing about some aspect of whatever is happening with the current weather: the heat vs. their tomatoes; the threat of frost to their citrus or succulent plants; gusty springtime northerly winds drying out the soil prematurely; and let’s not forget comparing plant damage due to a freak hailstorm.

Many gardeners are amateur meteorologists, with a yard full of devices that measure the air temperature, the rainfall, the humidity, the wind, and more. According to University of California Ag and Natural Resources climate scientist Daniel Swain, more care is needed as to where you place those weather sensors. After all, that thermometer that’s hanging outside your kitchen window may be reading much warmer than what is happening in your garden.

“There are genuine microclimates that can vary over that distance. If the thermometer is attached to your house, it might be warmer,” says Swain, who runs the informative Weather West YouTube page and on other social media outlets. “Presumably if it’s a cold night, you have the heater on inside. Some of that’s going to bleed outside a little bit near your house. If you have it hanging on a wall or an eave somewhere, it is going to exert perhaps a bit of a warming effect. And irrigation can affect the reading. Most people who are farmers or gardeners know that once you put water in the soil, once you put water on the plants, you kind of dampen the range of temperatures that you’re going to experience. By having moisture in some places more than others, you’re also going to actively, in some cases, create a temperature differential that’s different than where you might be measuring at your house or out on the driveway.”

Swain says more thought needs to go in to where you place that thermometer sensor for the most accurate readings for the plants of greatest concern.

“You’re measuring, technically, the temperature of a small increment of air immediately surrounding that thermometer device,” says Swain. “Imagine two different scenarios, the same parcel of land, the same home, and two thermometers within, five feet of each other. There’s not really a meaningful meteorological difference between the temperature across those five feet under normal circumstances. The numbers should be the same. But imagine that one of those thermometers is just sitting out there in direct sunlight. Maybe you’ve mounted it on a pole above a dirt field or over a concrete or asphalt driveway. That thermometer is going to read some awfully high values in the daytime and potentially some awfully low values in the nighttime. And that’s because you have the sun directly shining on the thermometer, heating the thermometer itself because of the sunlight is landing on the device itself. That thermometer is going to read a very high value. On a hot day, you might even get a value of 120 degrees on that thermometer. But as we define the surface temperature, the temperature at two meter height, so right around the top of my head, since I’m a little over six feet tall, that’s kind of a standard meteorological temperature measurement that’s used not just in science, but also for practical purposes