This paper explores the content knowledge of sixteen experienced teachers in an area of the Geography curriculum that has previously been investigated with students – tropical cyclone causes, patterns and processes. Data collected using a questionnaire, drawing task and semistructured interview enabled the analysis of the teachers’ conceptual knowledge and depth of understanding. Three categories of conceptual knowledge were identified including: concepts already understood by the teachers; concepts where understanding developed throughout the interview; and concepts that were less regularly understood and resistant to change. The paper concludes with the implications of these findings for classroom practice and the development of Geography teachers’ pedagogical content knowledge. Strategies for promoting the development of Geography teachers’ substantive (content) knowledge are also explored.