---
title: "Flags and codes"
date: "2026-06-16"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Flags and codes}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---




## What are flags/codes

The data output of the `weather_dl()` function include corresponding `_flag` columns for each data column. These columns are used by ECCC to add notes regarding measurements. 

Similarly, the data output of the `normals_dl()` function include corresponding `_code` columns. These columns are used by ECCC to add notes regarding the amount of data used to calculate the normals.

In the `weather_dl()` function if `format = TRUE` (the default), data corresponding to flags `M`, `NA`, and `[empty]` are all replaced with `NA` (if they are not already `NA`).

### Flags - Weather Data

The flags index can be accessed through the built in data frame: `flags`


|code    |meaning                                                             |
|:-------|:-------------------------------------------------------------------|
|A       |Accumulated                                                         |
|B       |More than one occurrence and estimated                              |
|C       |Precipitation occurred, amount uncertain                            |
|D       |Data subject to further quality control procedure                   |
|E       |Estimated                                                           |
|F       |Accumulated and estimated                                           |
|L       |Precipitation may or may not have occurred                          |
|M       |Missing                                                             |
|N       |Temperature missing but known to be > 0                             |
|S       |More than one occurrence                                            |
|T       |Trace                                                               |
|Y       |Temperature missing but known to be < 0                             |
|[empty] |Indicates an unobserved value                                       |
|^       |The value displayed is based on incomplete data                     |
|†       |Data that is not subject to review by the National Climate Archives |
|NA      |Not Available                                                       |

### Codes
In the `normals_dl`() function, codes are associated with each variable:


```
## As of weathercan v1.0.0 the default normals are 1991-2020. Note that these normals are in a
## different format from previous years. See ?normals_dl for more details or use `normals_years =
## '1981-2010'` to revert to the previous set of normals. This message is shown once per session
## 
## 
## The most current normals available for download by weathercan are '1991-2020'
## Using composite locations: BRANDON
```

```
## # A tibble: 26 × 35
##    period daily_average_c daily_average_c_code daily_maximum_c daily_maximum_c_code
##    <chr>            <dbl> <chr>                          <dbl> <chr>               
##  1 Jan              -16.7 A                              -11.4 A                   
##  2 Feb              -14.1 A                               -8.5 A                   
##  3 Mar               -7   A                               -1.6 A                   
##  4 Apr                3.1 A                                9.6 A                   
##  5 May               10.3 A                               17.4 A                   
##  6 Jun               16.2 A                               22.6 A                   
##  7 Jul               18.4 A                               24.9 A                   
##  8 Aug               17.7 A                               25.1 A                   
##  9 Sep               12.2 A                               19.5 A                   
## 10 Oct                4   A                               10.1 A                   
## # ℹ 16 more rows
## # ℹ 30 more variables: daily_minimum_c <dbl>, daily_minimum_c_code <chr>,
## #   maximum_daily_mean_c <dbl>, maximum_daily_mean_c_code <lgl>,
## #   maximum_daily_mean_c_date <date>, maximum_daily_mean_c_date_code <lgl>,
## #   minimum_daily_mean_c <dbl>, minimum_daily_mean_c_code <lgl>,
## #   minimum_daily_mean_c_date <date>, minimum_daily_mean_c_date_code <lgl>,
## #   minimum_daily_maximum_c <dbl>, minimum_daily_maximum_c_code <lgl>, …
```

For example, here, the code indicates that these temperature variables meet the WMO '3 and 5 rule' (no more than 3 consecutive and no more than 5 total missing for either temperature or precipitation).      

Older climate normals are in a different format, but the codes are the same


```
## # A tibble: 13 × 23
##    period temp_daily_average temp_daily_average_code temp_daily_max temp_daily_max_code
##    <fct>               <dbl> <chr>                            <dbl> <chr>              
##  1 Jan                 -16.6 A                                -11.1 A                  
##  2 Feb                 -13.6 A                                 -8.1 A                  
##  3 Mar                  -6.2 A                                 -1   A                  
##  4 Apr                   4   A                                 10.5 A                  
##  5 May                  10.6 A                                 17.8 A                  
##  6 Jun                  15.9 A                                 22.4 A                  
##  7 Jul                  18.5 A                                 25.2 A                  
##  8 Aug                  17.7 A                                 24.9 A                  
##  9 Sep                  11.8 A                                 18.9 A                  
## 10 Oct                   4.1 A                                 10.4 A                  
## 11 Nov                  -5.6 A                                 -0.5 A                  
## 12 Dec                 -14   A                                 -9   A                  
## 13 Year                  2.2 A                                  8.4 A                  
## # ℹ 18 more variables: temp_daily_min <dbl>, temp_daily_min_code <chr>,
## #   rain_extreme_daily <dbl>, rain_extreme_daily_code <chr>, rain_extreme_daily_date <date>,
## #   rain_extreme_daily_date_code <chr>, snow_extreme_daily <dbl>,
## #   snow_extreme_daily_code <chr>, snow_extreme_daily_date <date>,
## #   snow_extreme_daily_date_code <chr>, precip_extreme_daily <dbl>,
## #   precip_extreme_daily_code <chr>, precip_extreme_daily_date <date>,
## #   precip_extreme_daily_date_code <chr>, sun_extreme_daily <dbl>, …
```


### Codes - Climate Normals

The codes index for climate normals can be accessed through the built-in data frame: `codes`


|code |meaning                                                                                                                       |
|:----|:-----------------------------------------------------------------------------------------------------------------------------|
|A    |WMO '3 and 5 rule' (i.e. no more than 3 consecutive and no more than 5 total missing for either temperature or precipitation) |
|B    |At least 25 years                                                                                                             |
|C    |At least 20 years                                                                                                             |
|D    |At least 15 years                                                                                                             |