Weather: Data Collection, Instruments and Interpreting Climate Graphs

This guide covers 2.4, Weather, from Theme 2, The Natural Environment, in Cambridge IGCSE Geography 0460. It follows Coasts and shifts from landform processes to the practical skills of collecting, calculating with, and interpreting weather data – skills tested directly through data and graph-based exam questions rather than descriptive recall alone.

How weather data are collected

You need to describe how weather data are collected. This subtopic is built around a specific named set of instruments and the site they are housed in, described below, each measuring one particular weather variable under standardised conditions so that readings can be meaningfully compared over time and between locations.

The Stevenson Screen

You need to describe and explain the characteristics, siting and use of a Stevenson Screen: a louvred, white-painted wooden box that houses thermometers and other instruments. Its specific design features all serve a single purpose – ensuring temperature readings reflect the actual air temperature rather than being distorted by direct external influences. The white colour reflects solar radiation rather than absorbing it; the louvred sides allow free air circulation while blocking direct sunlight and precipitation from reaching the instruments inside; and it is sited at a standard height above the ground, away from buildings, trees or other obstructions that could create local, unrepresentative microclimates.

Named weather instruments

You need to know a specific set of instruments and what each measures: a rain gauge measures precipitation amount; a maximum-minimum thermometer records the highest and lowest temperatures reached over a period; a wet-and-dry bulb thermometer (hygrometer) measures humidity, using the difference in readings between a normal (dry bulb) thermometer and one with a wet fabric wick (wet bulb) around its bulb; a sunshine recorder measures the duration of bright sunshine; a barometer measures atmospheric pressure; and an anemometer and wind vane together measure wind speed and wind direction respectively. The syllabus also notes simple digital instruments now used for weather observations alongside these traditional devices, and observations of cloud type and amount as a further recorded measurement.

Calculations using weather instrument data

You need to be able to make calculations using information from weather instruments – for example, calculating a mean (average) daily or monthly temperature from a set of readings, calculating a temperature range from maximum and minimum readings, or calculating total rainfall over a period from daily rain gauge measurements. These are typically straightforward arithmetic operations, but the exam skill being tested is applying the correct calculation to weather data presented in an unfamiliar table or format, not the arithmetic itself.

Interpreting weather and climate graphs

You need to use and interpret graphs and other diagrams showing weather and climate data. This includes reading values directly from a graph, describing overall patterns or trends shown (such as a seasonal temperature or rainfall pattern), and comparing two locations’ data presented on the same or paired graphs. A common exam format pairs a temperature line graph with a rainfall bar chart on the same climate graph, requiring you to read and describe both together – for example, identifying the wettest and driest months, or describing the overall temperature range shown, directly from the graph rather than from memorised typical values.

A worked calculation example

A weather station records daily maximum temperatures of 28, 30, 27, 31 and 29 degrees Celsius over five days, and daily minimums of 18, 19, 17, 20 and 18 degrees over the same period. The mean maximum temperature is (28 + 30 + 27 + 31 + 29) / 5 = 29°C, and the mean minimum is (18 + 19 + 17 + 20 + 18) / 5 = 18.4°C. The diurnal (daily) temperature range for the highest single day is 31 − 20 = 11°C if using that day’s own maximum and minimum, or, more commonly in exam questions, the range between the mean maximum and mean minimum across the period is 29 − 18.4 = 10.6°C. Working through worked examples like this using a fresh, unfamiliar dataset each time – rather than only reviewing an already-completed example – is the most reliable way to prepare for this subtopic’s data-handling questions.

How to approach it

Learn each instrument paired directly with what it measures and its one key design feature (for example, hygrometer – humidity – compares wet and dry bulb readings), since exam questions frequently ask you to identify an instrument from a description of what it measures, or vice versa. Practise the standard weather calculations (mean, range, total) on unfamiliar data tables rather than only reviewing worked examples, since the specific skill being tested is applying the right calculation to new data under exam conditions. For graph interpretation, practise reading a paired temperature-and-rainfall climate graph specifically, since this combined format (rather than a single-variable graph) is the one most consistently used in this subtopic’s exam questions, and requires you to describe two variables’ patterns together rather than in isolation.

Why this subtopic matters beyond itself

The instruments, calculations and graph-reading skills built in 2.4 are not confined to Weather alone – they are the data-handling foundation for 2.5, Climate and natural vegetation, where the same temperature and precipitation data, aggregated over a full year, is used to characterise and compare entire climate types. A student who is fluent in reading a climate graph and calculating a temperature range here will find the equatorial-versus-hot-desert climate comparison in 2.5 considerably more straightforward, since it draws on exactly the same skills applied to longer-term, whole-climate data rather than short-term daily readings.

Official syllabus

Cambridge International, Cambridge IGCSE Geography (0460) syllabus for 2025 and 2026: official syllabus PDF, Subject content, section 2.4 “Weather”. Verified 2026-09-02.