diff --git src/wp-includes/date.php src/wp-includes/date.php
index c023574..3428bc2 100644
--- src/wp-includes/date.php
+++ src/wp-includes/date.php
@@ -304,8 +304,17 @@ class WP_Date_Query {
 
 		// Days per year.
 		if ( array_key_exists( 'year', $date_query ) ) {
-			// If a year exists in the date query, we can use it to get the days.
-			$max_days_of_year = date( 'z', mktime( 0, 0, 0, 12, 31, $date_query['year'] ) ) + 1;
+			/*
+			 * If a year exists in the date query, we can use it to get the days.
+			 * If multiple years are provided (as in a BETWEEN), use the first one.
+			 */
+			if ( is_array( $date_query['year'] ) ) {
+				$_year = reset( $date_query['year'] );
+			} else {
+				$_year = $date_query['year'];
+			}
+
+			$max_days_of_year = date( 'z', mktime( 0, 0, 0, 12, 31, $_year ) ) + 1;
 		} else {
 			// otherwise we use the max of 366 (leap-year)
 			$max_days_of_year = 366;
@@ -335,10 +344,10 @@ class WP_Date_Query {
 		);
 
 		// Weeks per year.
-		if ( array_key_exists( 'year', $date_query ) ) {
+		if ( isset( $_year ) ) {
 			// If we have a specific year, use it to calculate number of weeks.
 			$date = new DateTime();
-			$date->setISODate( $date_query['year'], 53 );
+			$date->setISODate( $_year, 53 );
 			$week_count = $date->format( "W" ) === "53" ? 53 : 52;
 
 		} else {
@@ -381,14 +390,23 @@ class WP_Date_Query {
 				continue;
 			}
 
-			$is_between = $date_query[ $key ] >= $check['min'] && $date_query[ $key ] <= $check['max'];
+			// If multiple values are passed, and one fails, throw a notice.
+			$is_between = true;
+			foreach ( (array) $date_query[ $key ] as $_value ) {
+				$is_between = $_value >= $check['min'] && $_value <= $check['max'];
+
+				if ( ! $is_between ) {
+					break;
+				}
+			}
+
 
 			if ( ! $is_between ) {
 
 				$error = sprintf(
 					/* translators: Date query invalid date message: 1: invalid value, 2: type of value, 3: minimum valid value, 4: maximum valid value */
 					__( 'Invalid value %1$s for %2$s. Expected value should be between %3$s and %4$s.' ),
-					'<code>' . esc_html( $date_query[ $key ] ) . '</code>',
+					'<code>' . esc_html( $_value ) . '</code>',
 					'<code>' . esc_html( $key ) . '</code>',
 					'<code>' . esc_html( $check['min'] ) . '</code>',
 					'<code>' . esc_html( $check['max'] ) . '</code>'
diff --git tests/phpunit/tests/date/query.php tests/phpunit/tests/date/query.php
index 82b6ffa..2169d88 100644
--- tests/phpunit/tests/date/query.php
+++ tests/phpunit/tests/date/query.php
@@ -960,6 +960,68 @@ class Tests_WP_Date_Query extends WP_UnitTestCase {
 		}
 	}
 
+	/**
+	 * @ticket 31001
+	 */
+	public function test_validate_date_values_should_process_array_value_for_year() {
+		$p1 = $this->factory->post->create( array( 'post_date' => '2015-01-12' ) );
+		$p2 = $this->factory->post->create( array( 'post_date' => '2013-01-12' ) );
+
+		$q = new WP_Query( array(
+			'date_query' => array(
+				array(
+					'compare' => 'BETWEEN',
+					'year' => array( 2012, 2014 ),
+				),
+			),
+			'fields' => 'ids',
+		) );
+
+		$this->assertEquals( array( $p2 ), $q->posts );
+	}
+
+	/**
+	 * @ticket 31001
+	 */
+	public function test_validate_date_values_should_process_array_value_for_day() {
+		$p1 = $this->factory->post->create( array( 'post_date' => '2015-01-12' ) );
+		$p2 = $this->factory->post->create( array( 'post_date' => '2015-01-10' ) );
+
+		$q = new WP_Query( array(
+			'date_query' => array(
+				array(
+					'compare' => 'BETWEEN',
+					'day' => array( 9, 11 ),
+				),
+			),
+			'fields' => 'ids',
+		) );
+
+		$this->assertEquals( array( $p2 ), $q->posts );
+	}
+
+	/**
+	 * @ticket 31001
+	 * @expectedIncorrectUsage WP_Date_Query
+	 */
+	public function test_validate_date_values_should_process_array_value_for_day_when_values_are_invalid() {
+		$p1 = $this->factory->post->create( array( 'post_date' => '2015-01-12' ) );
+		$p2 = $this->factory->post->create( array( 'post_date' => '2015-01-10' ) );
+
+		$q = new WP_Query( array(
+			'date_query' => array(
+				array(
+					'compare' => 'BETWEEN',
+					'day' => array( 9, 32 ),
+				),
+			),
+			'fields' => 'ids',
+		) );
+
+		// MySQL ignores the invalid clause.
+		$this->assertEquals( array( $p1, $p2 ), $q->posts );
+	}
+
 	/** Helpers **********************************************************/
 
 	public function date_query_valid_columns_callback( $columns ) {