---
title: Reading Update
slug: fourkites-api-reference/reading-update
description: Learn how customers with the Temperature Tracking package can receive real-time temperature notifications via a POST to their callback URL. Get valuable data on load identifiers, shipment details, location, temperature reading, and more. Contact your Cust
createdAt: 2023-04-14T06:25:18.000Z
---

Customers with the Temperature Tracking package can receive a POST to their callback URL notifying them of the temperature reading on the load.

If you are a customer interested in Temperature Tracking, please reach out to your Customer Success Manager.

```json
{ 
"MessageType": "TEMPERATURE_UPDATE",
"FourKitesLoadId": 1234,
"LoadNumber": "BOL12345",
"ProNumber": "PRO123",
"Shipper": "test-shipper",
"Tags": ["tag1", "tag2"],
"ReferenceNumbers": ["Ref1", "Ref2"],
"Location": "123 Address Street, New York, NY, USA",
"City": "New York",
"State": "NY",
"Country": "USA",
"Latitude": "40.7127",
"Longitude": "-74.0059",
"TemperatureReading": "40", 
"TemperatureUnit": "F", 
"Sensor": "sensor 1",
"OdometerReading": 12345,
"Timestamp": "2015-10-01T16:00:00-05:00",
"Timezone": "America/New_York",
"TimezoneShortName": "EST",
"TimezoneOffset" : -1800
}
```

## Field Definitions

| **Field Name**       | **Description**                                                                                                                                                       | **Key Always Present?** | **Value Always Present?** | **Conditions for the Key to be Present**                                                     | **Data Type**             | **Max Length**                                            |
| -------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------- | ------------------------- | -------------------------------------------------------------------------------------------- | ------------------------- | --------------------------------------------------------- |
| `LoadNumber`         | Unique shipment identifier from shipper's system                                                                                                                      | Yes                     | Yes                       | N/A                                                                                          | String                    | 65535                                                     |
| `Location`           | Street address, city, state, and country of latest temperature update, concatenated                                                                                   | Yes                     | Yes                       | N/A                                                                                          | String                    | 1024                                                      |
| `Latitude`           | Latitude where latest temperature update was received                                                                                                                 | Yes                     | Yes                       | N/A                                                                                          | String / Decimal          | 18 if String                                              |
| `Longitude`          | Longitude where latest temperature update was received                                                                                                                | Yes                     | Yes                       | N/A                                                                                          | String / Decimal          | 18 if String                                              |
| `MessageType`        |                                                                                                                                                                       | Yes                     | No                        | For this callback to be sent, the UpdateType should be equal to temperature\_reading\_update |                           |                                                           |
| `FourKitesLoadId`    | Unique load identifier from FourKites system if the load was successfully created (IsSuccess = true). The field will be null if the load creation failed in FourKites | Yes                     | No                        | N/A                                                                                          | Number                    | 20                                                        |
| `LoadNumber`         | Unique shipment identifier from shipper's system                                                                                                                      | Yes                     | No                        | N/A                                                                                          | String                    | 65535                                                     |
| `ProNumber`          | Shipment's PRO #                                                                                                                                                      | Yes                     | No                        | N/A                                                                                          | Number                    | 10                                                        |
| `Shipper`            | Unique shipper ID (permalink) from FourKites                                                                                                                          | Yes                     | No                        | N/A                                                                                          | String                    | No max, but realistically, not longer than 200 characters |
| `Tags`               | List of tags associated with the load (empty list when tags are not present)                                                                                          | Yes                     | No                        | N/A                                                                                          | Array of string           | 50 for each tag                                           |
| `ReferenceNumbers`   | List of additional reference numbers associated with the load (empty list when no reference numbers are associated with the load)                                     | Yes                     | No                        | N/A                                                                                          | Array of string           | No max                                                    |
| `City`               | City where latest temperature update was received                                                                                                                     | Yes                     | No                        | N/A                                                                                          | String                    | 1024                                                      |
| `State`              | State where latest temperature update was received                                                                                                                    | Yes                     | No                        | N/A                                                                                          | String                    | 1024                                                      |
| `Country`            | Country where latest temperature update was received                                                                                                                  | Yes                     | No                        | N/A                                                                                          | String                    |                                                           |
| `TemperatureReading` | Latest temperature reading                                                                                                                                            | Yes                     | Yes                       | N/A                                                                                          | String                    | 1024                                                      |
| `TemperatureUnit`    | Unit of measurement; Shorthand for Fahrenheit or Celsius (F or C)                                                                                                     | Yes                     | Yes                       | N/A                                                                                          | String                    | 1024                                                      |
| `Sensor`             | Compartment or sensor unit name that sent the latest temperature update                                                                                               | Yes                     | Yes                       | N/A                                                                                          | String                    | 1024                                                      |
| `OdometerReading`    | Odometer reading associated with the temperature update (provided only for loads moved by dedicated carriers)                                                         | Yes                     | No                        | N/A                                                                                          |                           |                                                           |
| `Timezone`           | e.g., Eastern                                                                                                                                                         | Yes                     | No                        | N/A                                                                                          | String                    | 50                                                        |
| `Timestamp`          | Time when the latest location update was received (in ISO 8601 format)                                                                                                | Yes                     | No                        | The locatedAt field will be converted to specific timezone and will be mapped.               | String in DateTime format | 30                                                        |
| `TimezoneShortName`  | e.g., EST                                                                                                                                                             | Yes                     | No                        | Depending on Timestamp                                                                       | String                    | 5                                                         |
| `TimezoneOffset`     | Offset in seconds from UTC. Western Hemisphere timezones will display a negative value.                                                                               | Yes                     | No                        | Depending on Timestamp                                                                       | \[+/-]Digits              | 10                                                        |