Climate has a huge impact on wine. How hot it gets during the growing season, how cold it gets during winter, annual precipitation, humidity, and wind patterns all affect how the grapes grow. The perfect season for a grapevine basically consists of a cool, wet winter that provides the soil with plenty of water; a spring with no late frosts and not too much rain; a warm and dry summer; and dry conditions right before harvest.

Grapevines go through a standard growth cycle every year. In spring, the vines experience “bud break,” when the small buds on the vines swell and open, revealing shoots of new, green growth. This is a delicate time, especially if warm weather brings bud break earlier than average, when the risk of frost is still prevalent. A late frost can decimate the early growth of the vines, setting them back for the entire season. Secondary buds will emerge if the primary ones are killed by frost, but they will not be nearly as strong.

Once daytime temperatures are consistently around 60 degrees Fahrenheit, the vines will begin to flower. The flowers are tiny, green, and tightly packed in clusters. Once bloom begins, pollination can occur. (Most grapevines used for wine grapes are self-pollinating, containing both male and female organs.) This is another point in the growing process that is very susceptible to weather; wind and/or rain can blow the tiny flowers off the vines, lowering fruit yields for the season.

The next stage is called “fruit set,” when the seed(s) and the grape form; this begins almost immediately after fertilization of the flowers. The grapes are green and hard, with little sugar and high acid levels. A month or two later, the grapes enter “veraison” when they change color, soften, and swell in size. Consequently, sugar levels rise and acid levels drop.

Depending on the grape type and conditions in the vineyard, it may be necessary to “thin the crop” in order to get better quality grapes. If too many flowers on the vine are pollinated and fertilized and become grapes, there is a greater risk of not under-ripened fruit come harvest time. The vine may not have the energy or ability to bring all of the grapes to maturity, so some vineyard managers will cut off some of the grapes to ensure the remaining fruit ripens fully.

Come harvest time, day-by-day weather conditions become extremely important. Rain right before planned harvest, for example, can significantly impact the quality of the grapes. The vines will push water into the grapes, and the grapes themselves will absorb moisture through their skins, creating fruit with higher water content and less concentrated flavors. At the same time, a vineyard that experiences a rainy August or September can sometimes be saved by a warm Indian summer at just the right moment. Wine grapes are incredibly finicky.

So how does all of this impact the wine you’re drinking? First, consider where the wine is grown. If it’s from a warm wine-growing region, like the Barossa Valley in South Australia or the around Mediterranean, the vines will probably not suffer from problems like late frosts or excessive rain, and low humidity will help keep fungal diseases and molds from forming. Droughts can be a problem but can be mitigated with irrigation techniques.

As a result of all of this, wine grapes from hot climate regions will:

• Likely have lower acidity and higher sugar levels. The grape itself is like an engine burning off acidity and creating sugar. The hotter the climate and the longer the growing season, the more sugar will be created.
• Higher alcohol content. Once the grapes are pressed and fermentation begins with the addition of yeast, alcohol is formed, fueled by sugar. More sugar in the juice equals more alcohol when fermentation is complete.
• Fuller-bodied, heavier wines. How viscous a wine is, or how heavy or light it feels, is determined by how much sugar and other compounds are in the grape. Warmer, longer growing seasons result in more of those compounds.
• More concentrated, fruit-forward flavors. Warm growing seasons with minimal rainfall means the grapes have lower water content. With a lower water-to-sugar ratio, the flavors become much more concentrated.

Obviously, cool-climate wine regions commonly produce the opposite: lighter-bodied wines with higher acidity, lower alcohol content, and more mineral or savory flavors mixed in with the fruit characteristics. Similarly, “Old World” wines tend to lean toward the cool-climate wines, while “New World” wines are commonly of the hot-climate variety. Of course, these are generalizations, and you will no doubt find heavier wines from cool-climate regions or high-acid wines from warm climate regions, but it’s good to keep these “rules” in mind when selecting wine or pairing it with food.

A few examples:

Syrah (or Shiraz) from Australia’s Barossa Valley is very fruit-forward, with flavors so concentrated it sometimes takes on a “candied fruit” or “jammy” flavor, overflowing with fresh blackberry and blueberry components. The wines are high in alcohol and full-bodied. Conversely, Syrah from much of France has the classic fruit backbone but takes on other savory characteristics, like garden herbs, leather, or licorice, and the wines are not as heavy and rarely exhibit the “candied” fruit aspect.

Likewise, Chardonnay from California’s hot-climate areas are famously rich, round, and low in acidity. The flavors are fruit-forward, sometimes tropical, and buttery. Compare these with Chardonnay from areas of France like Chablis or from the Finger Lakes in New York, and you’ll find far less concentrated fruit flavors and a more “steely” or mineral quality, as if chunks of granite or slate were thrown into the tanks during fermentation.

Again, these are generalizations, but they usually prove to be true. Using these “rules” as a guide can be particularly useful when pairing wine with food. Creamy pasta dishes, for example, might call for a white wine with higher acidity to cut through the cloying sauce: you might want something from a cool climate region, or from a grape with naturally high acidity — a topic for another day.