This is the Oregon Viticulture Website

Last updated 20 April 2026

We created this website in order to make available free, open-source software that can help evaluate locations in the Pacific Northwest for suitability as vinyards.

Our software focuses solely on climate. It does not deal with other equally important criteria, such as soil composition and drainage. Our approach to climate is through Growing Degree Days, or GDD. GDD is a cumulative measure of temperature during the growing season.

The software offered here is based on algorithms that calculate GDD from the amount of sunlight that falls on a field, taking into account the direction in which the field faces, its slope, altitude above sea level, latitude, and longitude. The software is absolutely free; devising it has been a labor of love that we wish to share with those who might profit from it. At this point in time we have programs for both Windows and Macintosh.

By examining data from 32 sites in western Oregon we have been able to find a reliable relationship between insolation, temperature, and time of year. Our software uses this relationship to calculate GDD. We can thus provide a single number that indicates whether the growing season at a particular site is adequate.

The software programs are small and are easy to use. You can download them from the link on the left side of your screen. We recommend, however, that you visit some of the other pages linked there in order to understand how the software works, and why it works.

Requests and questions may be sent to us at this address. For an update on modifications and extensions of the software, click here.

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