Last Spring Frost Date Finder
Locate last spring observed frost within caller seasonal window; -1 explicitly means no observed event and is not a validated frost-free date, calendar/hemisphere determined by caller.
Description
The last spring frost is the final frost observation within a chosen seasonal search window.
The last spring frost is the final frost observation within a chosen seasonal search window. An explicit index window lets the caller choose the relevant hemisphere, calendar and reporting period.1
Locate last spring observed frost within caller seasonal window; -1 explicitly means no observed event and is not a validated frost-free date, calendar/hemisphere determined by caller.
When to use Last Spring Frost Date Finder
Use this tool to locate last spring observed frost within caller seasonal window; -1 explicitly means no observed event and is not a validated frost-free date, calendar/hemisphere determined by caller.
Prepare the climate observations and any independently chosen thresholds or model parameters. Confirm units, daily coverage, time order and the intended seasonal window.
How to use Last Spring Frost Date Finder and understand its results
- Prepare the climate observations and any independently chosen thresholds or model parameters. Confirm units, daily coverage, time order and the intended seasonal window.
- Enter dailyMinimumTemperaturesC, seasonStartIndex, seasonEndIndexInclusive, callerFrostThresholdC using the field table and calculation rules, then run the tool.
- Read observedFrostFound, frostDayIndex. 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 |
|---|---|---|---|
| dailyMinimumTemperaturesC | Daily minimum temperatures c | list of number | Required |
| seasonStartIndex | Season start index | integer | Required |
| seasonEndIndexInclusive | Season end index inclusive | integer | Required |
| callerFrostThresholdC | Caller frost threshold c | number | Required |
Supply daily minimum temperatures in °C, a finite frost threshold and nonnegative integer start and end indices. The window is inclusive, its start may not exceed its end, and both must fall within the supplied list. A frost requires temperature strictly below the threshold. The tool returns the last qualifying zero-based index and a found flag; no qualifying frost returns index −1 and false.
frost_i = (Tmin_i < threshold); last index = max qualifying i in the inclusive search window Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| observedFrostFound | Observed frost found | boolean |
| frostDayIndex | Frost day index | number |
{
"input": {
"dailyMinimumTemperaturesC": [
2,
-1,
3,
-2
],
"seasonStartIndex": 1,
"seasonEndIndexInclusive": 3,
"callerFrostThresholdC": 0
},
"output": {
"observedFrostFound": true,
"frostDayIndex": 3
}
}Limitations and assumptions
The tool does not decide which dates count as spring or convert indices to dates. Equality with the threshold is not a frost under this rule. A false result only indicates no frost in the supplied observations and window, not that later frost is impossible.
Numeric inputs and returned numeric values must be finite; an unrepresentable returned value produces an error. 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. A successfully returned false flag is an evaluated outcome; its meaning is explained above.
Alternative or Complementary methods
Use First Fall Frost Date Finder: Locate first fall observed frost within caller seasonal window; -1 explicitly means no observed event and is not a validated frost-free date, calendar/hemisphere determined by caller. For a complementary task, use Frost-Free Period Length: Find longest observed contiguous frost-free daily period with explicit endpoint censoring; unlike one seasonal frost date, longest available span is not extrapolated outside coverage.
References
-
Last Spring Frost Date Finder — tool.io
Similar or alternative tools
- First Fall Frost Date Finder
Locate first fall observed frost within caller seasonal window; -1 explicitly means no observed event and is not a validated frost-free date, calendar/hemisphere determined by caller.
- Frost-Free Period Length
Find longest observed contiguous frost-free daily period with explicit endpoint censoring; unlike one seasonal frost date, longest available span is not extrapolated outside coverage.