> For the complete documentation index, see [llms.txt](https://swatplus.gitbook.io/io-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://swatplus.gitbook.io/io-docs/theoretical-documentation/section-1-climate/untitled/1-1.3-temperature/1-1.3.1-daily-air-temperature.md).

# 1:1.3.1 Daily Air Temperature

Daily Air Temperature SWAT+ requires daily maximum and minimum air temperature. This data may be read from an input file or generated by the model. The user is strongly recommended to obtain measured daily temperature records from gages in or near the watershed if at all possible. The accuracy of model results is significantly improved by the use of measured temperature data.

The variable tmp in the master weather ([weather-sta.cli](/io-docs/introduction-1/climate/weather-sta.cli.md)) file identifies the method used to obtain air temperature data. To read in daily maximum and minimum air temperature data, the variable is set to the name of the temperature data file(s). To generate daily air temperature values, tmp is set to "sim". The equations used to generate air temperature data in SWAT+ are reviewed in Chapter 1:3. SWAT+ input variables that pertain to air temperature are summarized in Table 1:1-5. 

Table 1:1-5: SWAT+ input variables that pertain to daily air temperature.

<table><thead><tr><th>Definition</th><th width="153">Source Name</th><th>Input Name</th><th>Input File</th></tr></thead><tbody><tr><td>Name of measured temperature input file (.tmp) . Set to "sim" to simulate data</td><td>tgage</td><td>tmp</td><td><a href="/pages/-Mb1mDEncU0CHo8l57G2">weather-sta.cli</a></td></tr><tr><td>Observed daily maximum temperature (<span class="math">\degree C</span>)</td><td>max temp</td><td>tmpmax</td><td><a href="/pages/-Mb1mbPcAjl2NJL2OPou">*.tmp</a></td></tr><tr><td>Observed daily minimum temperature (<span class="math">\degree C</span>)</td><td>min temp</td><td>tmpmin</td><td><a href="/pages/-Mb1mbPcAjl2NJL2OPou">*.tmp</a></td></tr></tbody></table>

See the description of the .tmp file on the [tmp.cli](/io-docs/introduction-1/climate/tmp.cli-and-temperature-data-files.md)  page for input and format requirements if measured temperature data is being used.