What Is Partly Cloudy?
Partly cloudy is a sky condition where both clouds and clear sky are present. Clouds cover a noticeable portion of the sky, but large areas remain unobstructed.
Conditions can change throughout the day as clouds develop, move or dissipate. A partly cloudy day may therefore alternate between periods of sunshine and periods when the sun is temporarily blocked by clouds.
Partly cloudy describes cloud cover rather than a specific type of weather. It can occur during warm or cold conditions and does not necessarily mean rain or snow is expected.
Related Conditions
| Condition | Description |
|---|---|
| Clear Skies | A sky condition with little or no cloud cover. |
| Scattered Clouds | Individual or groups of clouds spread across the sky with large clear areas between them. |
| Fair Weather Clouds | Small clouds that commonly develop during otherwise fair and settled weather. |
| Cumulus Clouds | Puffy clouds with relatively flat bases that often form as warm air rises during the day. |
| Increasing Cloudiness | A period when cloud cover gradually expands, often ahead of an approaching weather system. |
Related Alerts
| Alert | Description |
|---|---|
| Severe Thunderstorm Watch | Indicates that conditions are favourable for severe thunderstorms to develop. |
| Severe Thunderstorm Warning | Warns when a severe thunderstorm is occurring or expected to affect an area. |
| Tornado Watch | Indicates that atmospheric conditions are favourable for tornado development. |
| Frost Advisory | Issued when temperatures near the ground are expected to become cold enough for frost to develop during the growing season. |
| Wind Warning | Warns when winds are expected to become strong enough to create hazardous conditions. |
What Causes Partly Cloudy Skies?
Partly cloudy skies develop when conditions support some cloud formation without producing a continuous layer across the entire sky.
One common cause is uneven daytime heating. As the sun warms the ground, pockets of warmer air can rise into the atmosphere. If that air contains enough moisture, it cools as it rises and water vapour condenses into clouds.
This process frequently produces cumulus clouds. These clouds can be scattered across the sky with large areas of blue sky between them, creating partly cloudy conditions.
Changes in moisture and atmospheric stability can also affect how much cloud develops. Drier or more stable air may limit cloud growth, while increasing moisture and stronger rising motion can cause clouds to become more widespread.
Partly cloudy skies can therefore transition in either direction. Clouds may dissipate and leave clear skies, or increasing moisture may cause cloud cover to expand later in the day.
FAQ
Partly cloudy means clouds cover part of the sky while a substantial amount of clear sky remains visible.
Yes. If moisture and rising air increase, individual clouds can expand and merge until most or all of the sky becomes covered.
The terms are often used to describe similar mixtures of clouds and clear sky. The exact terminology used in forecasts can vary between weather services.