what does this symbol mean?

Weather map symbols

What the fronts, H and L, isobars, station plots, wind barbs and present weather symbols on a surface weather map mean.

Test yourself: Weather map symbols quiz

Fronts and boundaries 6 symbols

Pressure 2 symbols

Station plots 3 symbols

Present weather 5 symbols

About weather map symbols

A surface weather map shows the air at ground level at one moment: where the fronts are, where the pressure is high and low, and what each weather station reported. These pages describe what each symbol on such a chart means, from NOAA’s Weather Prediction Center (WPC) and JetStream school, the World Meteorological Organization’s manual on weather charts and the Met Office. They are not forecasts.

Fronts and boundaries

A front is the boundary between two air masses. WPC draws a cold front as a blue line with triangles and a warm front as a red line with semicircles, the symbols on the side towards which the front moves. An occluded front is purple with both, and a stationary front alternates red and blue. The WMO’s manual gives the same colours. A trough is a long area of low pressure: a wide orange dashed line on WPC’s charts, a plain black line on the Met Office’s. A dry line separates moist air from dry.

Pressure

H and L mark the centres of high and low pressure, blue and red on WPC’s charts, with the central pressure in millibars. Isobars join places of equal pressure, normally every 4 millibars according to the Met Office, and lie closer together where the wind is stronger.

Station plots

The station model packs one station’s report round a small circle: temperature at the upper left, pressure at the upper right, dew point at the lower left. The circle’s filling is the sky cover, in eighths, and the wind barb gives direction and speed, a long barb for each 10 knots, a short one for 5 and a pennant for 50.

Present weather

The WMO’s present weather table has a symbol for each kind of weather at the station: dots for rain, commas for drizzle, asterisks for snow, three bars for fog and a bracket with a zigzag arrow for a thunderstorm. Repeating a symbol means heavier precipitation, and a sideways S around it means freezing.

Sources

  1. WPC Product Legends: Surface Fronts and Boundaries, Product legend, NOAA National Weather Service, Weather Prediction Center, Surface Fronts and Boundaries
  2. Unified Surface Analysis Manual, Version 1, NOAA National Weather Service, Weather Prediction Center (with OPC, NHC and HFO), Chapter 3, Definitions
  3. Manual on the Global Data-processing and Forecasting System, Appendix II-4: Graphical representation of data, analyses and forecasts, WMO-No. 485, Appendix II-4 (as circulated to IPET-DRMM-III, Beijing 2015), World Meteorological Organization, 3.2 Symbols
  4. How to read synoptic weather charts, Learn about weather, Met Office, Isobars; Troughs
  5. Understanding weather charts, Key Stage 4 lesson plan, Crown Copyright, Met Office (hosted by MetLink, Royal Meteorological Society), Part A: Isobars
  6. JetStream Max: Surface Weather Plots, JetStream, the NWS online weather school, NOAA National Weather Service, Surface Weather Plots
  7. Station Model Information for Weather Observations, Sample station plot, NOAA National Weather Service, Weather Prediction Center, Wind
  8. JetStream Max: Surface Weather Plot Symbols, JetStream, the NWS online weather school, NOAA National Weather Service, Present Weather Symbols
  9. Reading the surface station model, Online Weather supplemental information, 9 February 1999, by Edward J. Hopkins, University of Wisconsin–Madison, Department of Atmospheric and Oceanic Sciences, Weather symbol convention

Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research