// Loading Google Charts version '45'. The 'current' version throws errors upon loading DataView
google.charts.load('45', {
  // Callback function when Google charts finish loading
  'callback': function() {
    jQuery(".region").change(drawChart);
    // Removed 'drawChart()', seems like you prefer a selection before drawing the chart
  },
  // Packages used on this page
  'packages': ['corechart']
});

function drawChart() {
  // Obtain the selected option value
  var region = jQuery(".region").find(":selected").val();

  // Construct a query with select statement based on the region value
  var query = new google.visualization.Query("https://docs.google.com/spreadsheets/d/1wLbWMwwu_bXcpxm8TlkNtkR4gbeqz_o8CuRzdDQMUaM/gviz/tq?gid=799372846&tq=select A," + region);

  // Execute the query
  query.send(handleQueryResponse);
};

function handleQueryResponse(response) {
  // Retrieve the data table
  var data = response.getDataTable();

  // Create a number formatter for formatting
  var formatter = new google.visualization.NumberFormat({
    pattern: '0'
  });
  // Formatting for first column
  formatter.format(data, 0);

  // Create another number formatter
  var formatter = new google.visualization.NumberFormat({
    pattern: '#,##0.0'
  });
  // Format the second column
  formatter.format(data, 1);

  // Set the chart area height
  var chartAreaHeight = data.getNumberOfRows() * 12;

  // Determine the chart's height
  var chartHeight = chartAreaHeight + 70;

  // Set x-axis labels or 'ticks'
  var xTicks = [];

  // Find the maximum amount for ticks
  var dataMax = google.visualization.data.group(
    data,
    // Modifier column to find max value across the entire table
    [{column: 0, type: 'string', modifier: function () {return '';}}],
    // Max column
    [{column: 1, type: 'number', aggregation: google.visualization.data.max}]
  );

  // 'Round up' to the nearest 1000
  var maxTick = Math.ceil(dataMax.getValue(0, 1) / 1000) * 1000;

  // Load the ticks array
  for (var i = 0; i <= maxTick; i = i + 1000) {
    xTicks.push(i);
  }

  // Build y-axis ticks, adding every year, potential font reduction or increased height may be necessary
  var yTicks = [];
  for (var i = 0; i < data.getNumberOfRows(); i++) {
    yTicks.push(data.getValue(i, 0));
  }

  // Chart options
  var options = {
    animation: {
      startup: true,
      easing: 'linear',
      duration: 750
    },
    annotations: {
      textStyle: {
        fontSize: 7
      }
    },
    title: jQuery(".region").find(":selected").text(),
    legend: "none",
    vAxis: {
      title: "Year",
      format: "0"
    },
    hAxis: {
      title: "Rainfall (in mm)"
    },
    height: chartHeight,
    chartArea: {
      height: chartAreaHeight,
      // Use number for exact height, string for percentage "100%"
      top: 70,
      right: 100,
      bottom: 100,
      left: 100
    },
    // Define bar height
    bar: {
      groupWidth: 7
    },
    // Specify x-axis ticks
    hAxis: {
      ticks: xTicks
    },
    // Configure y-axis settings
    vAxis: {
      // Year format
      format: '0',
      // Adjust text style for font size
      textStyle: {
        fontSize: 8
      },
      // Include tick marks
      ticks: yTicks
    }
  };

  // Generate data view from data table
  var view = new google.visualization.DataView(data);
  // Add calculated column for annotations - 'current' version may encounter issues here
  view.setColumns([0, 1, {
    calc: "stringify",
    sourceColumn: 1,
    type: "string",
    role: "annotation"
  }]);

  // Create and render the chart
  var chart = new google.visualization.BarChart(document.getElementById("chart"));
  chart.draw(view, options);

  // Re-render the chart upon window resizing
  // Removed 'window.addEventListener' as compatibility may vary across browsers
  $(window).resize(function() {
    chart.draw(view, options);
  });
};

.text {
  margin-bottom: 10px;
}

.region {
  text-align: left;
}

button {
  text-align: left;
  margin-left: 10px;
}

#chart {
  width: 100%;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
<script src="https://www.gstatic.com/charts/loader.js"></script>
<div class="text">
    Select a region below to know the annual rainfall in that region.
</div>

<div>
    <select class="region">
        <!-- Prefer this over 'optgroup' if a selection is required before drawing -->
        <option selected="selected" disabled>Please select a region...</option>
        <option value="B">Andaman &amp; Nicobar Islands</option>
        <option value="C">Arunachal Pradesh</option>
        <option value="D">Assam, Meghalaya</option>
        <option value="E">Bihar</option>
        <option value="F">Chattisgarh</option>
        <option value="G">Coastal Karnataka</option>
        <option value="H">Coastal Andhra Pradesh</option>
        <option value="I">East Rajasthan</option>
        <option value="J">East Madhya Pradesh</option>
        <option value="K">East Uttar Pradesh</option>
        <option value="L">Gangetic West Bengal</option>
        <option value="M">Gujarat Region, Dadra &amp; Nagar Haveli</option>
        <option value="N">Haryana, Delhi, Chandigarh</option>
        <option value="O">Himachal Pradesh</option>
        <option value="P">Jammu, Kashmir</option>
        ...
        
    </select>
</div>

<div id="chart">
</div>