Weather Index Insurance & What Does Deficit Rainfall Pay?
Cover the drought
Enter the rainfall trigger, exit level, measured rainfall and sum insured to get the payout fraction, payout amount and the shortfall in mm — parametric cover that pays on a measured trigger, no survey.
Weather-index insurance
Next: file the claim: you are owed ₹20,000 (0.5× the sum insured) for the 100 mm shortfall.
Index insurance pays on measured rainfall, not your actual crop loss — so there can be basis risk (you lose a crop yet rainfall stayed above trigger, or vice versa). Payout scales linearly between the trigger (0) and exit (full).
Weather index insurance — key facts
- Pays on
- a measured rainfall trigger
- No survey
- no field loss visit needed
- Above trigger
- no payout (rain adequate)
- Trigger → exit
- payout rises linearly
- At exit
- full sum insured paid
- Payout
- fraction × sum insured
- Trade-off
- basis risk vs speed
- Privacy
- Runs in your browser; nothing uploaded
Insurance that pays on the rain gauge
Traditional crop insurance waits for an inspector to survey your loss — slow, costly and easy to dispute. Weather index, or parametric, insurance flips that: it pays on an objective number, usually rainfall recorded at a reference station. If rain stays above the trigger, the crop is presumed fine and there's no payout; below the trigger, the payout climbs linearly with the shortfall until it reaches the full sum insured at the exit level. No surveyor, no claim visit — the gauge decides, so money reaches the farmer fast.
This tool computes the payout fraction, the payout amount, the rainfall shortfall in mm and the sum insured in 8 currencies, from your policy's trigger and exit. Use it to understand how a parametric product behaves, to estimate a deficit-rainfall payout, and to weigh the speed of index cover against basis risk. Pair it with the Crop Insurance Claim, Premium and Effective Rainfall tools to plan your weather protection.
Estimate the payout
What a rainfall shortfall pays under your policy.
Read the fraction
How the trigger and exit shape your cover.
No survey delay
Why parametric cover pays fast on a trigger.
Weigh basis risk
Speed and certainty against gauge-vs-field gap.
Frequently Asked Questions
What is weather index insurance?+
Weather index (parametric) insurance pays out based on a measured weather variable — typically rainfall recorded at a reference station — rather than on a survey of your actual field loss. If the measured value crosses a defined trigger, the policy pays automatically. It's fast and transparent because no claim visit or loss assessment is needed; the gauge decides the payout.
How is the payout calculated?+
Between the trigger and the exit level, the payout rises linearly with the shortfall. Payout fraction = (trigger − measured rainfall) ÷ (trigger − exit), capped at 0 above the trigger and at 1 (full payout) at or below the exit. The payout amount is that fraction × the sum insured. This tool computes the fraction, the amount and the shortfall for you.
What are the trigger and exit levels?+
The trigger is the rainfall level at which payouts begin — above it, there's no payout because rainfall is considered adequate. The exit is the level at which the full sum insured is paid — at or below it, the crop is assumed a total weather loss. Between trigger and exit, the payout scales linearly with how far rainfall fell short.
Why use a rainfall trigger instead of a field survey?+
A survey-based claim needs an inspector, takes time and can be disputed. A rainfall index uses an objective, automatically recorded number, so payouts are fast, predictable and free of claim disputes or surveyor visits. The trade-off is basis risk — your field might suffer more or less than the gauge implies — but for many farmers the speed and certainty are worth it.
What is basis risk?+
Basis risk is the gap between the measured index and your actual loss. The rainfall station might record adequate rain while your specific plot stayed dry, or vice versa, so you could get less (or more) than your true loss. Choosing a nearby, representative reference station and a well-set trigger reduces basis risk, but it can't be eliminated entirely.
What does the payout fraction mean?+
The payout fraction is the share of the sum insured you receive — 0 when rainfall is at or above the trigger, 1 (100%) at or below the exit, and a proportionate value in between. Multiplying the fraction by the sum insured gives the payout amount. The tool shows the fraction so you can see exactly how the trigger and exit shape your cover.
Does this fit India's weather-based crop insurance?+
Yes — the trigger/exit, linear-payout structure is the basis of weather-based crop insurance schemes (such as WBCIS) used for rainfall, temperature or humidity indices. This tool models the rainfall-deficit case; enter your scheme's trigger, exit, measured rainfall and sum insured to estimate the payout under its term sheet.
Can it model excess rainfall too?+
This tool models the deficit (drought) case, where payouts rise as rainfall falls below the trigger. Excess-rainfall or other indices follow the same linear trigger/exit logic but in the opposite direction. The deficit model covers the most common rainfall-shortfall product; for excess cover, mirror the trigger and exit accordingly.
Can I use this outside India?+
Yes. Parametric weather insurance is used worldwide for crops, and the trigger/exit/linear-payout maths is universal. Choose your currency and enter your policy's rainfall trigger, exit, measured rainfall and sum insured to estimate the payout anywhere.
Is this an official payout figure?+
No — it's a planning estimate. Real payouts follow your policy's exact term sheet, reference station data and definitions. Use this tool to understand how a parametric product works and to estimate likely payouts, then confirm against your insurer's term sheet.