In order to really be successful in growing those special plants from far away places, it's always good to have a thorough understanding of your local microclimate. There are many general patterns that determine the microclimates in pretty much everyone's yard, including effects such as a south facing exposure, a hillside, pockets where frost can accumulate, and exposure to sea breezes. Each of these effects will create special conditions which may or may not be condusive to a plant's success in your yard.

But before you can start with the really tiny microclimates in your yard, it behooves you to understand the overall microclimate of your region. Thanks to the advent of the internet, live and historical meteorological data for an increasing number of locations are available just a few mouse clicks away. Now, you can actually put away all those USDA and Sunset zone maps, and actually evaluate for your own self what kind of conditions actually prevail in your town. Often, those live measurements are even accompanied by live images so that you can check out how much sun your cherished plants are getting while you're at work or traveling.

Which sites are the most useful?

	Historical Data • California Weather Database • Western Regional Climate Center • NCDC US Data • NCDC Global Data Live Data • REINAS Instruments • Automated Weather Service

The sites that keep and display historical data at daily, or even hourly intervals are most valuable to the gardener. Based on such data, it's easy to quickly dispell any myths about what can really be grown. The facts are there, down to daily low and highs. For example, you can quickly take a look at what really happened at your location during the last cold events in California, in January 1972, December 1990, and December 1998. On the other hand, by looking at data over the past 50 years, you can also get a good idea on how often such events happen. Extreme temperature readings make it easy to discourage people from growing tender plants, but if such extremes only occur every 10 years, and for only a couple of days, then it becomes more straight forward to provide adequate protection for such a short time.

But before you jump to any conclusion about your climate, take into account that the temperature in your yard might still be quite different from what the official weather station down the street might be reading. We took a look at the December 1998 readings for all the stations around Santa Cruz, and the results varied significantly from locations to location. In the Delavega Golf Course, the lowest recorded temp. was 27F, while the official reading in Santa Cruz was 24 F. At UCSC, the lowest temperature was 29 F. What was different in these locations? Each station is at a different altitude, and not suprisingly, the highest location had the mildest reading.

The altitude effect was even more dramatic in Goleta, CA, just north of Santa Barbara. At the Santa barbara Municipal Airport in Goleta, CA, at an altitude of 35 feet, the lowest recorded temperature was a chilly 24 F. Yet, at the CIMIS station in the Goleta Foothills at an altitude of 635 feet, the temperature never dipped below 36 F. Considering that climate zone maps rarely take into account more than one weather station per town, it's easy to see how misleading zone maps can be. It certainly pays to evaluate all the weather station readings available in the vicinity of your garden.

Station Elev. 1998 1990 Goleta 640 ft 35 F 31 F Goleta 30 ft N/A 22 F Goleta 9 ft 26 F 20 F Santa Barbara 250 ft 33 F N/A Santa Barbara 5 ft 36 F 27 F Details

1990 and 1998 Freezes in Santa Barbara A major freeze hit California shortly before Christmas in December, 1990 and 1998. These freeze sent temperatures plunging into the low 20's in many Citrus and Avocado growing areas, causing millions of dollars in damage up and down the state. Most of Santa Barbara was spared the worst thanks to the moderating effect of the ocean and because of both city heat and good cold air drainage. But not everyone in town got the same treatment from mother nature.

The California Weather Database, run by the University of California Davis Statewide Integrated Pest Management Project, really packs a punch when it comes to a friendly Interface. The site contains data from numerous locations, including mainly CIMIS and NCDC stations throughout California. All of these stations are generally run professionally and provide very reliable data. The only drawback is that currently, only daily max/min values are available even though all CIMIS stations provide much more frequent readings. The more frequent readings are desirable for many reasons, including the ability to evaluate the absolute duration of freezes and to calculate real degree day and chill readings based on integration over each 24 hour period.

The National Climate Data Center (NCDC) is another great site to obtain daily max/min readings for the US, but we found that the number of stations included for California was rather small. Many stations, most notably those in Santa Cruz County are ommitted. The user interface is not bad, but it's not always obvious where to find the data. What's great about CIMIS is that they do have a repository of World Climate Readings which can be useful to make comparisons between our local micro climates and the native climates of many plants grown here.

Full size view (61 kbytes)

Comparing Quito, Ecuador to Monterey, CA Thanks to the international data available on the internet, it is possible to look up weather readings in Andean cities. We made the interesting comparison between Quito Ecuador and monterey, CA, and found the two cities to have very similar temperature readings. The image above compares the temperature readings of both cities during the year 1994.

The Western Regional Climate Center, run by the Nationa Weather Service, has some very useful climate summaries with a friendly user interface. You won't find much data for specific events short of daily record max/min readings, but the data available there is really the best summary data currently accessible on the net. The site definitely deserves an award. It is worth to note that the National Weather Service also hosts a great weather page for the Bay Area and Central California. This page gets updated often and provides links to all the relevant weather information for our area. It is worth visiting this page often during the Winter. There you will get ample warnings of impending freezes for our area.

The web also offers live weather readings for many locations. There are three sites we have found very useful. REINAS Instruments, Automated Weather Service, and Weather Underground. The REINAS page is great because it gives access to both REINAS and CIMIS live readings. But we found that the REINAS instruments themselves give rather strange readings on many occasions. Most of the time, this is the case because the stations are placed on the roofs of buildings, and as a result, the temperature readings will be either too cold during the day or too warm during the night. But the main purpose of these instruments is to track wind, so it is not surprising that they do not comply to the National Weather Service Standard of placing instrumention 5 feet above the ground. But the CIMIS readings are exellent, provided they are working. Unfortunately, most of the time the CIMIS readings do not work properly.

The Automated Weather Service offers live readings for many locations, and in most instances, these readings are quite accurate. The readings are based on a network of instruments placed mainly on public sites such as schools and museums, and there again, if the instruments are placed on the roof, temperature measurements will be highly affected by wind conditions. Strangely enough, AWS has no stations in Santa Cruz County.

There are many additional commercial sites which provide weather readings, including for example Yahoo, the Weather Channel, and others. But the main drawback we found with all of these sites is that they do not cater to a very sofisticated audience. Locations are given by averaging by the closest neighboring station. Enter a given city for which they do not have a live reading, and you will get a reading from a nearby station. The only problem is, they do not tell you that the reading comes from a nearby station. While this might work for the rest of the country, it does not work for the California coastal zone, where a distance as small as 5 miles can mean a 20 degree difference.

One notable exception is Weather Underground. This service provides very detailed reports and informs you when the current displayed conditions are actually from another city nearby. The site also features international readings, and allows other web sites to add weather icons to their own pages. We highly recommend this site.

Instead of relying on Sunset zones or otherwise, consult all of the online weather resources before you rule out growing a particular plant. Even if the plant is too tender to be grown in your area, at the very least, you will find out how often you can expect to have to protect it.

The Cloudforest Gardener

Link to many online weather readings