Consecutive Dry Days Counter

Find complete dry runs in a caller gap-free observed daily sequence using strict precipitation below supplied threshold; endpoints may be truncated by observation coverage, not proven climate-season boundaries.

Description

Consecutive dry days reveal persistence of low rainfall.

Consecutive dry days reveal persistence of low rainfall. A dry-day threshold establishes whether small measured amounts interrupt a run.^[1]

When to use Consecutive Dry Days Counter

Use this tool to find complete dry runs in a caller gap-free observed daily sequence using strict precipitation below supplied threshold; endpoints may be truncated by observation coverage, not proven climate-season boundaries.

Prepare the climate observations and independently chosen model parameters. Confirm units, daily coverage, chronological order and the intended seasonal window.

How to use Consecutive Dry Days Counter and understand its results

Prepare the climate observations and independently chosen model parameters. Confirm units, daily coverage, chronological order and the intended seasonal window.
Enter dailyPrecipitationMm, callerDryDayUpperThresholdMm using the field table and calculation rules, then run the tool.
Read longestConsecutiveDryDays, dryRunStartIndices, dryRunLengthsDays. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
dailyPrecipitationMm	Daily precipitation mm	list of number	Required
callerDryDayUpperThresholdMm	Caller dry day upper threshold mm	number	Required

Supply a nonempty list of nonnegative daily precipitation in mm and a nonnegative upper threshold. Only rainfall strictly below it counts as dry. The tool returns all maximal dry runs with zero-based starts and lengths and their maximum length. With no dry runs, the lists are empty and the maximum is zero.

dry_i = (P_i < threshold); longest duration = max dry-run length, or zero

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
longestConsecutiveDryDays	Longest consecutive dry days	number
dryRunStartIndices	Dry run start indices	list of number
dryRunLengthsDays	Dry run lengths days	list of number

json

{
  "input": {
    "dailyPrecipitationMm": [
      0,
      0,
      2,
      0,
      3
    ],
    "callerDryDayUpperThresholdMm": 1
  },
  "output": {
    "longestConsecutiveDryDays": 2,
    "dryRunStartIndices": [
      0,
      3
    ],
    "dryRunLengthsDays": [
      2,
      1
    ]
  }
}

Limitations and assumptions

A zero threshold makes no nonnegative rainfall value dry. The series must represent consecutive days without gaps. Runs touching its edges may be incomplete, and the calculation does not declare a drought category or season boundary.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Numeric lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Wet Spell Length Analyzer: Analyze full consecutive wet spell distribution at a caller inclusive precipitation threshold; supplied sequence must have no missing days and zero means no observed qualifying spell. For a complementary task, use Cold Spell Duration Index CSDI: Calculate cold CSDI minimum-temperature spells against caller independently calibrated day-of-year percentiles with strict exceedance and minimum run; threshold ties excluded, gap-free coverage required.

References

Consecutive Dry Days Counter — tool.io

Similar or alternative tools

Wet Spell Length Analyzer
Analyze full consecutive wet spell distribution at a caller inclusive precipitation threshold; supplied sequence must have no missing days and zero means no observed qualifying spell.
Cold Spell Duration Index CSDI
Calculate cold CSDI minimum-temperature spells against caller independently calibrated day-of-year percentiles with strict exceedance and minimum run; threshold ties excluded, gap-free coverage required.