Possible Clues:

• Distinctive theory about additional line on map
• Displayed by weatherman in his other map
• Just as hot all along what is a different one that's grand
• Perhaps it's not the same number, but it is the same temperature along here
• Line joining places of equal temperature
• That seems grand with a difference, but equally hot along the line
• That's not the same temperature all along it that gets to be so grand
• Mother is prepared to show the same level of warmth
• This is not the same thousand, all in line
• That line is not the same thousand, it seems