Climate Normals, Drought and Agricultural Water
What the record shows about climate, drought and water — and where the record stops.
Three sources underlie this page: 55,924 values from NOAA’s 1991–2020 climate normals, the U.S. Drought Monitor’s weekly assessments, and FAO’s irrigation statistics.
They are four different kinds of statement and they look alike on the page. A normal is what thirty years averaged to. An assessment is what an author judged. A reported statistic is what a country told FAO. An agency estimate is what FAO worked out when a country said nothing. Each value here says which it is, because a reader who cannot tell them apart will read all four as measurements.
These are averages, assessments and reported statistics about places. None of them is a measurement of a field, a prediction of a season, or a statement about what a crop will yield.
- Values
- 55,924
- States with normals
- 50
- Countries with water data
- 197
- Forecasts published
- 0
What this page will not say
Every one of these is a step from exposure to impact. Knowing that a state was in severe drought and that a crop grows there establishes exposure; what it cost is a different question, and the step between them is the whole of the claim.
- Crop loss attributed to drought
- Requires crop stage at the time of stress, soil moisture, whether the field was irrigated and how it was managed. Knowing a state was in D2 and that a crop grows there establishes exposure, not damage, and the step between them is the whole of the claim.
- Yield impact of a climate condition
- Requires a yield model with its assumptions, its calibration and its error. None is published here, and a number produced without one would be an opinion wearing a statistic’s clothes.
- Water stress for a farm or field
- Every water figure here is national and every drought figure is state-wide. Nothing in this corpus resolves to a farm, and presenting an area statistic as one would tell a reader something about their own land that no source said.
- Future drought risk
- Would require a forecast or a projection, and this corpus holds neither. A past frequency is not a future probability, and computing one from 140 weeks of assessments would be a model this project has not built and could not defend.
Four kinds of statement, kept apart
- climate-normal6,850 values
- A 1991–2020 average, not a measurement of any year.
- assessment42,000 values
- A judgement drawn by an author from several indicators.
- reported-statistic2,676 values
- A figure the country officially reported.
- agency-estimate4,398 values
- A figure the agency estimated or imputed.
- measurementnone held
- A reading taken by an instrument. Daily and hourly station observations exist and are freely published, but a corpus that carried them would be carrying a weather record rather than a reference, and every page would need a freshness guarantee this project cannot make. The normals derived from those measurements are published instead.
- forecastnone held
- An expectation for a period that has not happened. Seasonal outlooks are published by NOAA’s Climate Prediction Center as probabilities, not as values, and a probability shift rendered beside a normal reads as a prediction of the number next to it. Nothing here forecasts a season.
- projectionnone held
- A modelled outcome under a stated scenario. Climate projections are conditional on emissions scenarios, and a projection shown without its scenario is a prediction. AgricultureID publishes no climate projection, and in particular publishes no deterministic statement about future agricultural loss.
A climate normal is what 1991–2020 averaged to at that station. It is not what any year was and not what any year will be; a season that matches it is ordinary, not forecast.
D0 is not drought
The Drought Monitor describes D0 as a precursor to drought and a category that areas pass through while recovering. It is counted separately everywhere on this site; folding it in would add more than twenty points to the average state’s drought figure.
- —
- No drought category · not counted as drought
- D0
- Abnormally dry · not counted as drought
- D1
- Moderate drought
- D2
- Severe drought
- D3
- Extreme drought
- D4
- Exceptional drought
The Drought Monitor is drawn each week by an author who weighs several indicators together with reports from local observers. It is an assessment of conditions, not an instrument reading, and each map applies to one week.
Irrigation capacity is not irrigation use
Land equipped for irrigation is infrastructure that could be watered. Area actually irrigated is what was. They are different figures for the same country in the same year, and reading the first as the second overstates agricultural water use.
| As the source names it | What it measures | Values |
|---|
| Land area equipped for irrigation | capacity | 4,695 |
| Agriculture area actually irrigated | use | 1,341 |
| Cropland area actually irrigated | use | 739 |
| Land area actually irrigated | use | 299 |
38% of these figures are a country’s own official statistic. The rest carry FAO’s flag saying it estimated or imputed them, and that flag travels with every value on this site.
Growing degree days need their base
- growingDegreeDaysBase50:
- Accumulated above a 50°F base with no upper limit (NCEI element ANN-GRDD-BASE50).
Discarded: ANN-GRDD-TB5086
Documented as: Long-term averages of annual growing degree days with base 50F limit 86F
The column in this archive is inverted against its own definition and is in places physically impossible. Honolulu, the warmest station in the set, carries 0.0 while its base-50 normal is 10,242; Barrow, Alaska carries 16,841. Across 6,666 stations the coldest two hundred have a median of 9,016 and the warmest two hundred a median of 191 — the opposite of what a growing degree day does. Twelve stations exceed 13,140, the largest annual total a base-50 ceiling-86 accumulation can reach. Whether this is an upstream problem or a subtlety this corpus cannot resolve, the values cannot be explained, so they are not published. ANN-GRDD-BASE50 is published instead: it orders with temperature as it must, and satisfies the bound every base-50 accumulation satisfies.
1,370 values not published.
Datasets, and what each is entitled to say
NOAA NCEI — U.S. Climate Normals, 1991–2020 (annual, by station)
climate-normal6,850 valuesClimate normals are the baseline every statement about an unusual season is implicitly made against, and they are the one climate quantity that can be published without predicting anything.
About: One weather station, at its own coordinates. A station normal describes the station and nothing around it; no county, state or field figure is derived from it here.
What it does not tell you
- A normal is an average of 1991–2020. It is not a measurement of any year and not a forecast of any year.
- Only NCEI’s Standard tier is published here: at least 24 of the 30 years available at the station itself.
- Values are in the source’s units. Nothing is converted to metric.
- Growing degree days are published on one base only. NCEI’s base-50 ceiling-86 element is discarded here: it runs the wrong way against temperature and in places exceeds what that accumulation can reach.
Source: U.S. Climate Normals, 1991–2020 · U.S. Climate Normals
U.S. Drought Monitor — state drought area, categorical
assessment42,000 valuesDrought is the climate risk with the most immediate agricultural consequence, and the Drought Monitor is the authoritative weekly account of it in the United States — provided it is presented as the assessment it is.
About: A whole state, as a share of its land area. Not a share of its farms, its cropland or its population, and not a statement about any particular place inside it.
What it does not tell you
- The map is an assessment drawn by an author, not an instrument reading and not a model output.
- D0 is “abnormally dry” and is not drought.
- Each map is valid for one week; outside that week it is history.
- A share of a state’s area says nothing about what any farm in it experienced.
Source: U.S. Drought Monitor · U.S. Drought Monitor
FAOSTAT — land use: irrigation (by country, annual)
agency-estimate7,074 valuesAgricultural water is where climate risk becomes an agronomic constraint, and irrigation area is the one water quantity published consistently enough across countries to compare at all.
About: A whole country or territory. Regional and world aggregates are excluded, because including them alongside the countries inside them would count the same land twice.
What it does not tell you
- Area equipped for irrigation is infrastructure. Area actually irrigated is use. They are different numbers and are never merged.
- Fewer than half of these values are figures a country officially reported; the rest carry FAO’s own flag saying it estimated or imputed them.
- A national area says nothing about which crops were watered or when.
Source: FAOSTAT — Land, Inputs and Sustainability: Land Use · FAOSTAT
Drought assessments and climate normals for individual states appear on their state pages, where a weekly assessment is shown only while the week it applies to is still current.