# Chinese Sanfu & Sanjiu Seasonal Period Date Calculator

> Chinese Sanfu & Sanjiu Seasonal Period Date Calculator is a paid API for AI agents from api.cn402.com, paid per call via x402, $0.016/call, status unknown (last checked 2026-09-13).

Returns exact Gregorian date ranges for the three sanfu (三伏, dog-day summer heat) periods and three sanjiu (三九, coldest winter) periods for a given year, used in traditional Chinese medicine seasonal therapy planning.

## Facts

- Endpoint: GET https://api.cn402.com/sanfu/sanjiu
- Price: $0.016/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/api-cn402-com-09fb99ed
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_3rxm4N2ODuzyqBtL25gTW

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability api-cn402-com-09fb99ed
```

Example prompt: What are the exact sanfu (三伏 dog days) and sanjiu (三九 coldest period) dates for 2025 so I can plan a TCM seasonal therapy schedule?

## When to prefer this

Use this endpoint when you need precise, algorithmically-derived dates for Chinese folk seasonal periods (sanfu and sanjiu) — especially for traditional Chinese medicine scheduling, moxibustion therapy timing, health app content, or any application that needs to anchor events to the Chinese hottest and coldest seasonal windows.

## Known failure modes

- Missing or invalid year parameter returns an error
- Year out of supported range returns an error or empty result
- Network or payment failure (402 unpaid) prevents response

## How this service works

Chinese dog days, sanfu, 三伏, hottest period of year, Chinese coldest period, sanjiu, 三九, Chinese folk seasonal periods, Chinese medicine seasonal therapy, fu tian, 伏天, Chinese summer heat, Chinese winter cold. Exact dates for the three sanfu (dog day) periods and three sanjiu (coldest) periods of a given year. Used in traditional Chinese medicine seasonal therapy.

## Output

Returns the start and end dates for each of the three sanfu (初伏, 中伏, 末伏) summer heat periods and each of the three sanjiu (一九, 二九, 三九) coldest winter periods for the requested year, expressed as Gregorian calendar dates.

## Example request

```json
{
 "year": 2025
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "year": {
   "type": "string",
   "description": "Year (required)"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/api-cn402-com-09fb99ed/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.cn402.com](https://www.zero.xyz/host/api.cn402.com/llms.txt)