How to read an hour-by-hour weather graph

An hour-by-hour weather graph is easiest to read as a story moving from left to right. Start at now, scan toward the time you care about, and look only at the two or three conditions that could change your plan. You do not need to decode every line before the graph becomes useful.

The quick method

1. Find the time window for your decision. Are you choosing when to walk the dog, leave for work, start a run, photograph a sunset, or cover plants overnight?
2. Follow the main trend. Notice whether temperature, rain, or wind is rising, falling, arriving, or clearing.
3. Add one supporting layer. Rain probability helps qualify rain amount; gusts add context to average wind; dew point changes how a warm hour may feel.
4. Choose a window, not a perfect hour. Forecasts describe a changing atmosphere, so a robust two-hour window is often more useful than treating one timestamp as a promise.

Weathergraph uses a shared visual language across the app, widgets, and Apple Watch. Your graph may show fewer layers because it is configurable.

Read each layer as a question

Graph layer	What it represents	The useful question
Horizontal position	Time, from earlier to later	When does the change reach me?
Day/night background and sun glow	Darkness, daylight, and especially sunny periods	Will this happen in daylight, shade, or strong sun?
Cloud layer	Expected cloud cover	Is a brighter or clearer interval opening up?
Temperature curve	Actual or “feels like” temperature, according to your setting	Is it warming, cooling, crossing freezing, or staying steady?
Blue or white precipitation bars	Forecast rain or snow amount	When does precipitation become meaningful, and how intense is it expected to be?
Light-blue precipitation area	Probability from 0–100%	How confident is the forecast that measurable precipitation reaches this location?
Wind shape and arrows	Wind speed, direction, and gusts	When will wind become inconvenient or important to the activity?
Blue dotted line	Humidity or dew point	Will a warm period also become more humid or muggy?

The layers are not independent. A warm hour in full sun with a high dew point can feel different from the same temperature in cloud and breeze. A small rain amount with high probability suggests a different plan from a larger possible amount with low probability.

Rain probability is not rain amount

A 70% chance of rain does not mean rain for 70% of the hour, nor does it tell you how hard it will rain. The US National Weather Service defines probability of precipitation as the chance that measurable precipitation will occur at a particular location during a specified period. See the NWS definition.

That is why a useful graph shows probability and amount separately:

• Probability asks whether precipitation is likely to reach you.
• Amount asks how much is forecast if precipitation occurs.
• Timing asks when the bars begin, peak, and end.

Read all three before deciding whether you need an umbrella, a waterproof layer, a different route, or simply a later departure.

A worked example: finding a comfortable run

Imagine the temperature peaks at 31 °C in mid-afternoon, rain probability rises after 18:00, and the dew point remains high until evening. The single warmest or driest icon does not answer the real question.

A more useful reading is:

1. Exclude the hottest, sunniest hours if heat is a concern.
2. Look for the period when temperature and sunshine begin to fall.
3. Check whether wind helps or becomes disruptive.
4. Check whether the first rain bars arrive before the planned finish.
5. Use official heat or severe-weather guidance when conditions may be dangerous.

The result might be a window such as 19:00–20:30—not because one number is “best,” but because several relevant trends line up. For more on warm, humid conditions, read dew point vs. humidity.

Why the graph can change

Every point to the right of “now” is a forecast, not a measurement of the future. New observations and new model runs can shift the timing, amount, or shape of a trend. The farther ahead you look, the more useful it is to read the broad pattern rather than fixate on a precise minute.

If two apps show different curves, the reason may be their forecast source, model cycle, processing, or presentation—not necessarily a broken graph. See why weather forecasts disagree for a practical comparison method.

How Weathergraph is designed to be read

Weathergraph can display up to seven days on a continuous hourly timeline. You choose which weather metrics deserve space, whether the temperature curve represents actual or “feels like” conditions, and how much time the chart shows. The aim is not maximum data for its own sake; it is keeping the relationships you care about visible in one glance.

The same chart language carries into Weathergraph widgets and Apple Watch complications, although smaller spaces necessarily show less detail. If the graph ever appears inconsistent with the forecast text or another Weathergraph surface, treat that as something to investigate—not something an explainer should wave away—and contact support with the location, time, source, and a screenshot.

Sources and limits

• The National Weather Service precipitation-probability definition distinguishes the chance of measurable precipitation from its duration or amount.
• Weathergraph's layer descriptions and settings are documented in the Weathergraph FAQ.
• A weather graph helps compare forecast conditions. It does not replace local warnings, observations, or professional guidance for weather-sensitive or safety-critical decisions.