Free Climate Graph Generator (Climograph Maker)

A climate graph puts the twelve months of a place on one chart: temperature as lines and precipitation as bars. Choose a location, load the 2001 to 2025 average from NASA POWER, open an EPW weather file or type your own values, and this climate graph generator draws a clean climograph for your climate analysis sheet. It is free, there is no sign up, and an EPW file you open is read in your browser, never uploaded.

How to use this climate graph generator

1. Set the site. Pick a city from the list, or type the latitude and longitude. South and west are negative. If you chose a place in the wind rose or bioclimatic chart tool on this site more recently, the graph opens on that place.
2. Load the data. With NASA POWER selected, press Load climate data. One click sends two requests: the daily temperatures for 2001 to 2025 and the monthly climatology for humidity, rainfall and solar radiation. You can also choose EPW weather file, or Type monthly values and fill in the table under the graph.
3. Choose what is drawn. Switch between °C and °F and between mm and inches. Tick or untick the daily maximum and minimum band, the record maximum and minimum, the humidity panel and the solar radiation panel. The band and the humidity panel are on by default.
4. Read the summary. Under the graph you get the annual mean temperature, the warmest and coldest month, annual precipitation, the wettest and driest month, mean humidity and annual solar radiation. The table lists every value by month, with a Year column.
5. Export. PNG is drawn at twice the export width, SVG stays sharp on a presentation board, and CSV gives you the full monthly table. Add a chart title if you want one; otherwise the graph is titled automatically. You can export in light or dark colours, or print the tool on its own.

How to read a climograph

Read the temperature lines first. The orange line is the mean temperature of each month, and the shaded band around it runs from the mean daily minimum to the mean daily maximum. The highest point of the line is the warm season, the lowest is the cold season, and the gap between them is the annual range. A line that swings far between summer and winter belongs to a continental climate; a nearly flat line with almost no annual range is tropical or strongly maritime.

Then read the width of the band. That is the daily temperature range: the difference between a typical afternoon and a typical night. It matters as much to a building as the mean does. A wide band means cool nights even in a hot month, which you can use to cool the structure. A narrow band means the night brings little relief.

Finally read the bars against the temperature. The blue bars are monthly precipitation, on their own scale on the right. Rain in the warm months points to a monsoon or summer rain pattern. Rain in the cool months and dry summers points to a Mediterranean pattern. Rain spread evenly through the year is typical of temperate oceanic climates. Below the main graph, the humidity panel adds the relative humidity of each month on a fixed 0 to 100% scale, and the optional solar radiation panel adds the daily solar energy on a horizontal surface in kWh/m².

A climate graph for an architecture climate analysis sheet

On a site analysis board the climograph usually comes first, because it sets the scene for everything after it: when it is hot, when it is cold, when it rains and how humid the air is. A typical climate analysis sheet then adds the sun, the wind and a strategy chart:

• Climate graph: temperature, rainfall and humidity by month, from this tool.
• Sun path: where the sun is in each season, from the sun path diagram generator.
• Wind rose: prevailing wind by season, from the wind rose generator.
• Bioclimatic chart: which passive strategies the months call for, from the bioclimatic chart generator.

The location you choose here is carried over to the wind rose and bioclimatic chart tools, so the whole sheet describes the same point. The climate graph and the bioclimatic chart also share the same NASA POWER data saved in your browser, so once you have loaded a place in one, the other can draw it without a new request. Keep the source line that the tool prints on the image; it says where the numbers came from.

Mean, mean daily maximum and record values

The graph can show three kinds of temperature, and they answer different questions.

• Mean temperature is the average of every day in the month, day and night together. It is the single number for comparing climates.
• Mean daily maximum and minimum are the averages of each day’s high and each day’s low. They describe the typical afternoon and the typical night, and they are the values to design with: shading, ventilation and heating needs follow them.
• Record maximum and minimum are the warmest daily maximum and the coldest daily minimum of that month across all 25 years. They are the extremes a building has to survive, not the conditions it lives in most of the time.

The difference is easy to get wrong with NASA POWER data. Its monthly climatology contains a parameter called T2M_MAX, and for Istanbul in January it is about 17.5 °C. That is not a typical January afternoon: it is the warmest moment of all the Januaries in the period. The mean daily maximum for the same month, worked out from the daily series, is about 8.7 °C. To keep the values consistent with each other, the generator takes all of its temperatures, the mean, the daily maximum and minimum and the records, from the same NASA POWER daily series for 2001 to 2025, and labels them separately.

From the climate graph to design decisions

A climograph does not design a building, but it tells you which questions to ask first.

• Heavy rain months point to roof pitch, overhangs, gutters and drainage sized for the wettest month, and to covered outdoor space for the season when people cannot sit in the open.
• A wide daily range in the hot months points to thermal mass and night ventilation: heavy walls that soak up the afternoon and give it back to a cool night. Our guide to thermal mass in building design explains how to size it.
• Hot months with a narrow range and high humidity point to shade, light construction and cross ventilation instead. See designing homes that stay cool in hot climates.
• Long cold seasons point to compact form, insulation and glazing placed to collect winter sun.

For a direct reading of which strategies each month needs, plot the same place on the bioclimatic chart.

Where the climate data comes from

There are three common sources of monthly climate data for a site, and each has its place.

• NASA POWER (power.larc.nasa.gov, NASA Langley Research Center) publishes values derived from the MERRA-2 reanalysis and satellite observations, for a grid cell of roughly half a degree. It covers any point on land or sea, it is free and public, and it gives you a consistent period, here 2001 to 2025. Because it is a grid average, it can differ from a station on a coast, in a valley or in a dense city centre.
• EPW weather files describe one typical year, built from real months picked from many years of station records. They are the input for energy simulation, and free collections such as climate.onebuilding.org cover stations around the world. A typical year is good for typical conditions and poor for extremes, because unusual months are left out on purpose.
• National weather service normals are 30 year station averages; the current World Meteorological Organization standard period is 1991 to 2020. If your local service publishes them for a station near the site, you can type them into the table.

With NASA POWER, precipitation arrives as a daily rate in mm per day and is multiplied by the days in each month to give a monthly total, with February counted as 28.24 days to allow for the leap years in 2001 to 2025. Checked against NASA’s own monthly sums for Istanbul, the largest monthly difference was 0.14 mm. With an EPW file, the tool works out the monthly mean, the mean daily maximum and minimum, the relative humidity, the precipitation total and the solar radiation from the hourly records; the record values are then the extremes found in that one file.

Typing your own monthly values

Choose Type monthly values when you have figures from a local station, a textbook or a brief. Mean temperature and precipitation are required for all twelve months. The mean daily maximum and minimum are optional, but give both or neither, and the maximum must be at least the mean, which must be at least the minimum. Relative humidity and solar radiation in kWh/m² per day are optional and draw their panels when you fill them in.

If you loaded NASA POWER or an EPW file first, Copy the loaded values fills the table so you can correct only the months you need. Switching between °C and °F, or between mm and inches, converts the numbers you have typed, so the table never mixes units.

Climate types at a glance

A few patterns are worth recognising, because they show up immediately on a climograph.

• Hot dry: high temperature line, a wide band between day and night, and almost no bars. Shade and mass are the first moves.
• Hot humid: a flat, high temperature line with a narrow band, rain in most months and a humidity panel that stays high. Ventilation and shade come before mass.
• Temperate: a moderate arc through the year with rain in every month. The building has to handle both a heating season and a mild summer.
• Cold: a deep winter trough, often below zero, and a short summer peak. Insulation, airtightness and solar gain lead the design.

Frequently asked questions

What is a climograph?

A climograph, or climate graph, is a chart of one place’s monthly temperature, drawn as a line, and monthly precipitation, drawn as bars, over a typical year. It shows the warm and cold seasons and the wet and dry seasons at a glance.

Where does the data come from?

From NASA POWER (NASA Langley Research Center), averaged over 2001 to 2025, or from an EPW file you open, or from values you type. The source is printed under the graph and in the CSV.

Why is the record maximum so much higher than the mean daily maximum?

The record maximum is the warmest single day of that month in 25 years. The mean daily maximum is the typical afternoon. Design with the mean daily maximum and check the record when you need to know the extreme.

Can I use my own weather data?

Yes. Open an EPW file, which is read in your browser and never uploaded, or choose Type monthly values and fill in the table with figures from a local station.

Can I change to Fahrenheit and inches?

Yes. The graph, the table, the CSV and the exported image all follow the units you choose, and typed values are converted when you switch.

Why does my EPW graph have no rain bars?

Many typical year EPW files carry no precipitation. When the file has none, the graph shows temperatures only. Load NASA POWER for the same place to get rainfall.