Mondulkiri Coffee Climate: Rainfall, Temperature, Elevation, and Seasonality

Published field research around Sen Monorom gives a useful baseline for Mondulkiri coffee climate: the studied Coffea canephora farms averaged about 700 meters above sea level, the area's annual mean temperature was reported at 22.9°C, and long-term mean annual rainfall was about 2,203 mm. Coffee growers in the study described flowering around March and harvest beginning around November.

Those figures help explain why Robusta can grow in Mondulkiri, but they should not be turned into a simple claim that climate automatically produces Fine Robusta. Farm management, cherry maturity, processing, drying, storage, and roast still determine whether environmental potential becomes cup quality.

What is the climate like in Mondulkiri's coffee area?

Mondulkiri is cooler than much of lowland Cambodia because of its upland terrain.

A peer-reviewed study of three Coffea canephora plantations around Sen Monorom reported a tropical climate with an annual mean temperature of 22.9°C and mean annual rainfall of 2,203 mm for the study area.

During the researchers' own one-year measurement period from late November 2017 to late November 2018, total rainfall reached 2,427 mm. The measured annual average temperature was also 22.9°C, with a recorded minimum of 15°C and maximum of 36°C.

That range shows why a single annual average can hide important seasonal extremes.

Coffee does not experience a yearly average. It experiences hot afternoons, cool dry-season mornings, heavy rain events, and changing soil moisture.

How high are coffee farms around Sen Monorom?

The three plantations in the published study averaged about 700 meters above sea level.

That is useful evidence for those farms, not a province-wide altitude label.

Mondulkiri contains varied terrain. Some farms sit lower or higher, and a buyer should request the actual farm or lot elevation if elevation is being used as a quality claim.

Robusta can be grown across a wide altitude range internationally. Elevation affects temperature and growing conditions, but "high altitude" by itself is not a quality score.

For OCC, 700 meters should be cited as the average elevation of the studied Sen Monorom plantations rather than repeated as the elevation of all Mondulkiri coffee.

How much rain does Mondulkiri receive?

Rainfall is substantial, but it is seasonal.

The study area's long-term mean annual rainfall was reported at about 2,203 mm. During the field-measurement year, the site received 2,427 mm across 143 days with at least 1 mm of precipitation.

The highest monthly rainfall recorded during that measurement period was 553 mm in May 2018. A single day in May recorded 125 mm.

These numbers illustrate two things.

First, Mondulkiri has enough rainfall to make water management a central coffee issue.

Second, annual rainfall alone says little about when the water arrives.

Heavy rain during drying or flowering can create very different problems from the same amount of rain spread evenly across the year.

When is the rainy season in the studied coffee area?

For the 2017–2018 field period, researchers classified the rainy season from March 17 to November 23 and the dry season from November 27 to March 16.

Season boundaries vary from year to year, so these dates should not be presented as a permanent calendar.

The broader pattern is what matters: a long wet season followed by a drier period around harvest and the months before flowering.

Growers interviewed for the study said coffee flowering generally occurs in March at the end of the dry season. Harvest occurs around November at the beginning of the dry season.

That sequence connects farm operations directly to climate.

Why does a dry period matter for Robusta flowering?

Coffee flowering is linked with water stress and the return of moisture.

A dry period can place coffee trees into a resting phase. Rain after that period can help trigger synchronized flowering.

If rainfall becomes irregular, flowering can become less synchronized. That can create cherries at different maturity stages on the same tree, increasing the labor needed for selective harvesting.

For Mondulkiri, the traditional pattern of a dry period before March flowering therefore matters beyond irrigation. It affects crop timing.

Climate change may alter that pattern. OCC should avoid predicting the exact impact without local long-term data, but the mechanism is important enough to monitor.

When is Mondulkiri coffee harvested?

Published farm research and local grower information point to harvest beginning around November.

The 2021 shade study measured coffee yield in November and December 2017. Growers told the researchers that harvest generally occurs in November at the beginning of the dry season.

Historical reporting from Mondulkiri has also described farmers finishing harvest around December.

The practical harvest window can extend beyond one month because farms, varieties, flowering events, and weather differ.

For traceability, a supplier should provide the actual harvest period for the lot rather than using a generic "Mondulkiri harvest season" label.

Does Mondulkiri's temperature suit Coffea canephora?

The published mean temperature of 22.9°C sits within commonly cited suitable ranges for Coffea canephora.

The same study notes that Robusta is generally associated with warmer conditions than Arabica and cites an approximate optimum mean annual temperature range of 22–26°C for Robusta.

That does not mean every hour outside 22–26°C damages the crop. The field site itself recorded temperatures from 15°C to 36°C during the measurement year.

Plant response depends on duration, water status, shade, soil, wind, and growth stage.

The more useful conclusion is that Sen Monorom's annual climate can support Canephora, while seasonal extremes still require farm management.

What did the Mondulkiri shade study find?

The study compared shaded and sunny parts of three Robusta plantations.

It found no significant difference in measured coffee yield, bean size, bean weight, or fruit ripeness between shaded and sunny sites under the conditions studied.

Soil moisture, however, was generally higher in shaded plots.

This matters because the dry season can create water stress. Shade reduces direct solar energy and can reduce evaporation from the soil surface.

The result does not prove that every Mondulkiri farm should use the same shade percentage. Shade effects depend on tree species, density, pruning, competition, rainfall, farm design, and disease pressure.

It does show that agroforestry in the studied farms did not create the yield penalty some farmers might expect.

What kind of soil was documented on the studied farms?

The three research sites were described as having latosol with a clayey texture through the soil profile.

That is a useful description of those particular sites.

It should not become a claim that all Mondulkiri coffee grows in one uniform soil type. Provincial landscapes vary, and farm-level soil analysis is more useful for agronomy than a regional marketing phrase such as "red volcanic soil" unless the geology is actually documented.

For coffee buyers, soil is difficult to connect directly to flavor without intermediate evidence. Soil affects plant nutrition and water relations. It does not transfer a simple flavor note into the bean.

OCC should describe soil as an agronomic factor rather than a tasting-note shortcut.

Does higher elevation make Mondulkiri Robusta better?

Not by itself.

Elevation often lowers temperature and can change ripening dynamics. It can also interact with rainfall, cloud cover, and disease pressure.

But quality still depends on genetics, ripeness, harvest selection, processing, drying, storage, and roast.

A 700-meter Fine Robusta lot with excellent selective picking and drying can outperform a higher-elevation lot with poor processing.

Buyers should use elevation as one part of a lot description, not as a substitute for cupping and quality data.

What are the main climate risks for Mondulkiri coffee?

Water timing is one of the clearest risks.

Too little soil moisture during a prolonged dry period can stress trees. The field study recorded periods when soil moisture in sunny plots fell below the threshold the researchers used to indicate water deficit.

Too much rain can create other problems, including erosion, disease pressure, difficult field access, and slow drying after harvest.

Irregular rain around flowering can spread the flowering period and make selective harvesting more complicated.

High temperatures combined with dry soil can increase stress even when the annual mean temperature looks suitable.

These risks explain why climate suitability should not be described as a static advantage.

Does climate determine Fine Robusta cup quality?

No.

Climate sets the growing environment. It influences plant stress, flowering, fruit development, and harvest timing.

Fine Robusta quality is decided through the entire production chain.

A suitable climate cannot compensate for unripe cherry, uncontrolled fermentation, slow rewetting-prone drying, bad storage, or an unsuitable roast.

Coffee Quality Institute evaluates Fine Robusta through green and sensory quality rather than through altitude or climate alone.

This is an important distinction for Cambodia. Mondulkiri has environmental conditions that can support quality development, but quality must still be produced lot by lot.

How should roasters use climate information?

Use it to understand the origin, not to predict the flavor by itself.

A roaster can ask whether the lot was harvested early or late in the season, whether heavy rain affected drying, whether shade was used, and whether multiple flowering events created mixed cherry maturity.

Those questions connect climate to processing decisions.

"Grown at 700 meters with 2,200 mm rainfall" is descriptive information.

"Therefore it tastes like chocolate and tropical fruit" is not a defensible conclusion without sensory data.

The cup should supply the flavor claim.

Frequently asked questions

What is the average temperature in Mondulkiri's studied coffee area?

A peer-reviewed study around Sen Monorom reported an annual mean temperature of 22.9°C.

How much rain does the area receive?

The study cited mean annual rainfall of about 2,203 mm. Its one-year measurement period recorded 2,427 mm.

What elevation is Mondulkiri coffee grown at?

Three studied Sen Monorom plantations averaged about 700 meters above sea level. Other farms can differ.

When does coffee flower in Mondulkiri?

Growers interviewed in the study said flowering generally occurs around March at the end of the dry season.

When is coffee harvested?

The same study reported harvest beginning around November. Farm-level harvest dates can extend into December or beyond.

Does shade reduce Robusta yield in Mondulkiri?

In the three plantations studied, shade did not significantly reduce measured yield or bean size, while shaded sites generally retained more soil moisture.

What the climate evidence means

Mondulkiri's coffee climate is not mysterious. Around Sen Monorom, published field data show a cool tropical upland environment with substantial rainfall, a distinct dry period, farms around 700 meters in the study sample, flowering near the end of the dry season, and harvest beginning as the dry season returns.

Those conditions help explain why Coffea canephora can succeed there.

They do not guarantee Fine Robusta. Climate creates the opportunity. Farming and post-harvest work decide what reaches the cup.

Sources and technical references

Peer-reviewed field study: "Does Shade Impact Coffee Yield, Tree Trunk, and Soil Moisture on Coffea canephora Plantations in Mondulkiri, Cambodia?" Sustainability, 2021.

Mondulkiri provincial agriculture reporting on coffee expansion and production.

Coffee Quality Institute, Fine Robusta quality evaluation and Q Robusta education materials.