Enjoying a delicious cup of coffee may sometimes feel as simple as grind-brew-enjoy, but the reality is there’s a lot that has been going on before the flavours of the drink you love come to life in your cup.
The delicate tastes and sumptuous aromas that make up your coffee’s flavour are formed many hundreds of miles away from your kitchen, created by the environment in which the coffee cherries grow.
Lets take a journey around the world to discover just how rainfall, and temperature affect the growing coffee beans that become our favourite drink.
The different climates of the coffee belt
Specialist coffee is grown in the ‘Coffee Belt’, a region between the Tropics of Cancer and Capricorn that provides the perfect combination of warm temperatures, seasonal rainfall, and specific altitudes that the delicate nature of coffee demands.
Even within this strip of the world not everything is the same. Some areas have long dry seasons, others are high up in mountains where the nights are cool, while many experience torrential rains. It is this range of different conditions that gives each region and grower their unique coffee taste.
It’s a matter of time and temperature
Two of the greatest influences on coffee flavour are time and temperature. When the coffee has the time to mature slowly, it produces more complex flavours, developing a richer, more nuanced bean. Coffee beans that grow faster have simpler flavour profiles.
This is because the sugars build gradually when the bean develops slowly, resulting in a more floral aroma, higher acidity, and a greater range of distinct taste characters. That acidity itself leads to a more citrusy brightness that can make the final drink livelier.
When the altitude is higher, the growing coffee takes longer to ripen. This is why coffee grown high up in the mountains is typically well-regarded. The cooler climate slows down the cycle of growth, allowing the flavours to take their time to unfold.
This doesn’t mean that more rapidly harvested coffee beans are of a poorer quality - far from it. Taste is subjective and there are many coffee aficionados who are seeking beans with lower acidity and a more chocolatey quality. Coffee grown in warmer low-lying climates such as the highlands of Brazil, produces a sweeter, nutty flavour that’s full-bodied.
Rainfall and its impact on growing coffee
Rain is another major contributor to your coffee flavours. It can affect the sweetness of the drink, change the clarity of the flavours, and determine the richness of your coffee.
- Low rainfall - Drier conditions slow growth and enhance sweetness. The growing coffee bean is more stressed as it tries to bloom and creates more sugar as it ripens. This leads to beans with a richer, more syrupy flavour.
- Moderate rainfall - The balanced growing conditions that are experienced when the rain is in the middle of the spectrum allow the coffee beans to grow steadily. Flavours are well-rounded as there’s a balance of acidity and sweetness.
- High rainfall - More rain means faster growth and larger, more rapid, crop development. This can dilute the flavours and lead to a milder coffee. Acidity is weakened and the sugars are stretched.
As with temperature and time, the level of rain significantly affects the taste of the bean, either concentrating or diluting the flavours built up in its biology.
The difference between temperature and rainfall
Both temperature and rainfall can affect how quickly the coffee grows, but they do so in different ways - a coffee bean that’s grown quickly because it’s warm develops differently to a rapidly maturing bean that’s accelerated due to high humidity.
Warmth will speed up the ripening process but will still allow for sugar development and density - especially if other conditions such as altitude and rainfall are correctly balanced. This leads to full-bodied, sweet, and nutty coffees.
Excessive rainfall, however, boosts growth without concentration. The flavour can be underdeveloped through being over-watered, leading to a weaker profile.
It’s not just about speed - it’s about what’s happening inside the bean during its maturing. Too much water can result in a bloated bean that lacks complexity.
Finding your preferred coffee climate
Looking to discover your favourite region for coffee? Consider the factors of temperature and rainfall together to find a bean that’s perfect for you:
| Desired taste | Ideal temperature | Ideal rainfall | World regions |
| Full-bodied, sweet, and nutty | Warm | Moderate | Brazil, Nicaragua |
| Earthy and rich with low acidity | Warm | Low | India, Indonesia |
| Bright, citrusy, and floral | Cool | Moderate to low | Ethiopia, Kenya |
| Fruity and complex | Cool | High | Rwanda, Burundi |
| Smooth and chocolatey | Mild | Moderate | Colombia, Guatemala |
| Delicate and balanced | Mild | Moderate to high | Costa Rica, Panama |
Climate and Coffee Processing
It is not just the growth of coffee that is dependant on climate - it also changes how the coffee bean is processed once it has been harvested. Each region has slightly different drying and fermentation techniques that will affect the final flavour.
There are three common coffee processing methods: sun-dried or natural processing, washed processing, or semi-washed ‘honey’ processing - and each produces a different flavour.
Sun-dried or natural
As the name suggests, sun-dried processing involves the whole coffee cherry being laid out in the sun to dry. It’s a favoured process in hot, dry climates where there is little rainfall to worry about. The cherries can take several weeks to dry, during which time they are turned regularly to prevent mould from forming. Then, the outer layers are removed to reveal the bean within.
Sun-dried coffee beans are fruitier and full-bodied, with tastes of berries or jam, often likened to wine. They are bold and can feel heavier than other coffees.
Washed or wet
Also called ‘wet processing’, washed cherries are pulped before any drying occurs, removing the skin and most of the fruit before taking the beans and fermenting them in water tanks to break down the remaining fruit layers - known as mucilage - that still clings to the desired coffee bean. The beans are then washed clean before being dried (either in the sun, or in machine dryers).
Coffee that has been processed wet is clean and bright, with high acidity and floral and citrus flavours. It is common in wet regions due the level of water required for the process.
Honey or semi-washed
A middle-ground process, honey processed coffee has the skin removed before drying. The mucilage remains around the beans during the drying stage, and forms a honey-like texture that gives the process its name.
Honey processing balances the flavour and acidity of the coffee, resulting in a silky textured cup that has greater body than washed beans, but more brightness and clarity than sun-dried.
Like natural processing, the semi-washed process needs a dry climate free of excessive rainfall.
From mountain to cup
Next time you pick your beans, take some time to really consider the lifecycle of the coffee so far. Are you about to grind something that once basked in the sunlight high up a mountain, or has it been given a light fruitiness thanks to tropical rainfall? Was it left to dry with its sticky fruity ‘honey’ in place to give it balance, or has it been washed clean to promote floral touches?
Understanding how rainfall and temperature determine the flavour of your coffee will deepen your appreciation for the drink as well as helping you select beans from the right coffee climate for your personal taste.
Considering the craft that goes into nurturing your coffee beans, it feels right to treat them with equal care in the final stages of brewing. Store them properly to protect them from damaging light and air, grind them with a premium Niche Zero or Niche Duo grinder, and brew them to perfection using your chosen method. That delicious cup really has come a long way!