Palmer Drought Severity Index
NOAA NCEI nClimDiv · Monthly, ~1 week lag · latest period 2026-09-01 · vintage 2026-10-30
Latest period — 2026-09-01
| Area | Drought index |
|---|---|
| Nevada | -7.12 |
| Carson City | -3.38 |
| Churchill | -5.13 |
| Clark | -4.82 |
| Douglas | -2.13 |
| Elko | -7.28 |
| Esmeralda | -4.23 |
| Eureka | -7.34 |
| Humboldt | -5.69 |
| Lander | -5.81 |
| Lincoln | -5.08 |
| Lyon | -5.49 |
| Mineral | -5.45 |
| Nye | -5.05 |
| Pershing | -5.72 |
| Storey | -4.21 |
| Washoe | -4.91 |
| White Pine | -7.20 |
Methodology
The Palmer Drought Severity Index (PDSI) from NOAA's nClimDiv dataset, monthly, beginning in 1895. PDSI is a unitless index, not a measurement.
Reading the scale. Negative is dry, positive is wet, and roughly:
| Range | Conventional label |
|---|---|
| 4.0 and above | extremely moist |
| 2.0 to 3.99 | moderately to very moist |
| -1.99 to 1.99 | near normal |
| -2.0 to -2.99 | moderate drought |
| -3.0 to -3.99 | severe drought |
| -4.0 and below | extreme drought |
The index is cumulative: it carries the preceding months' moisture balance forward, so a single wet month lifts it only partway and a long dry run drives it well past -4. Nevada's statewide value has spent much of 2025 and 2026 below -3.
Not comparable across climates as a drought severity. PDSI is calibrated to each location's own history, so -3 in Elko and -3 in Alabama both mean "severe relative to normal here", not the same amount of water missing.
Derivation and revisions are as for precipitation: area-weighted averages of 5 km grid-point estimates from GHCN-Daily, with the most recent two years updated monthly and the full record restated on a version change. Each of our runs stores a new vintage rather than overwriting.