Climate and monthly weather forecast
Pennsylvania, USA

Pennsylvania experiences a humid continental climate with hot and humid summers and cold winters (Köppen climate classification Dfa) in the majority of the state. Delaware in the southeast, Maryland in the south, West Virginia in the southwest, Ohio in the west, New York in the north, the Canadian province of Ontario in the northwest, and New Jersey in the east, border the state. The southeast corner displays a humid subtropical climate (Köppen Cfa) due to the diverse topography of the state.

Pennsylvania, the Keystone State, is part of the Mid-Atlantic and Northeast states of America and consists of mountains, high plains, rivers, river valleys, coastal plains, lakes, and many other natural features. The Appalachian Mountains divide the state into two parts - the western part is colder than the east and is more rainy and snowy. Lake Erie, the largest water body with 51 miles of coastal shoreline, lies in the northwest of the state, while the Allegheny Plateau is in the east. Pennsylvania also has 57 miles of coastline along the Delaware Estuary but exceptionally, does not have a border with the Atlantic Ocean.

Summers are warm to hot and humid in the state, but few days go beyond 95°F (35°C). Rainfall peaks during the summer with a chance of thunderstorms. Spring is warm, wet, and prone to floods, especially in March and April. Autumn is mild in the early days and gradually cools down with the progress of the season - the fall foliage is extravagantly beautiful.
The best time to visit Pennsylvania is from May to October, but it is a good idea to avoid the rush of the summer crowd, which is the peak tourist season due to school vacations.

December to February is the worst time to visit Pennsylvania due to the extreme cold. The ground is white, the roads are icy, and the air is chilly. Snowstorms are frequent during the winter and deposit a large amount of snow. Blizzards can close roads and even stall highways and towns for long periods. Fog often accompanies the dark clouds, and sunshine is at a premium.
Most of the tourists leave Pennsylvania by November at the end of the fall season, and only budget travelers and snow enthusiasts remain during the winter.

Spring in Pennsylvania is marked by warmth and wetness. With temperatures pleasantly fluctuating between 50°F (10°C) to 70°F (21.1°C), the state comes alive with blossoming flora. However, with the beauty also comes the challenge of occasional flooding, especially during March and April. Rain showers are relatively common, giving the earth a refreshed and revitalized appearance. The season paints the state in a multitude of colors, offering an ideal setting for nature enthusiasts.

Summer in Pennsylvania is characterized by temperatures that range from 75°F (23.9°C) to 95°F (35°C). Nighttime offers a slight respite with temperatures falling between 55°F (12.8°C) and 70°F (21.1°C). July stands out as the warmest month, with the mercury rarely touching 100°F (37.8°C). Thunderstorms and rains peak during this season, bringing with them occasional heavy downpours and the brilliance of post-rain sunsets.

Autumn sees Pennsylvania transitioning from the heat of summer to the cold of winter. Early autumn maintains mild temperatures, but as the weeks go by, the state starts cooling down significantly. This season showcases Pennsylvania in its most splendid form, with trees donning hues of gold, orange, and red. The fall foliage becomes a sight to behold, attracting numerous photographers and nature lovers to the state's scenic spots.

Winters in Pennsylvania can be harsh, with temperatures often falling between 19°F (-7.2°C) and 30°F (-1.1°C). January is the coldest month, with temperatures frequently dipping below 0°F (-17.8°C). Snowstorms are a common occurrence, blanketing the state with an average snowfall of 23" (584mm). Especially in the mountainous interiors and areas near Lake Erie, snowfall can exceed 100" (2540mm). The season, while chilly, transforms Pennsylvania into a winter wonderland, much to the delight of snow enthusiasts.

January in Pennsylvania is distinguished as the coldest month of the year, with the mercury frequently venturing below 0°F (-17.8°C). The average temperatures for this month hover from 19°F (-7.2°C) to 33°F (0.6°C). The state's geographical disparities, especially the mountainous regions, play a vital role in influencing its winter climate. Weather in January »

February in Pennsylvania carries forward the cold spell from January, though the temperatures begin to show a slight rise as the month progresses. On average, temperatures during February range from 20°F (-6.7°C) to 35°F (1.7°C). Weather in February »

March in Pennsylvania marks the transition from winter's firm grasp to the gentle embrace of spring. As the month advances, the state experiences a noticeable shift in temperatures, which usually range from 28°F (-2.2°C) to 45°F (7.2°C). Weather in March »

April in Pennsylvania heralds a more consistent spring ambiance, with temperatures generally fluctuating from 37°F (2.8°C) to 57°F (13.9°C). As the month unfolds, snow's likelihood diminishes considerably, giving way to moderate rainfall and occasional thunderstorms. Weather in April »

May in Pennsylvania is a delightful month where spring fully blossoms and introduces hints of the approaching summer. Temperatures typically lie between 47°F (8.3°C) and 67°F (19.4°C), with the state experiencing a consistent warmth that isn't too overpowering. Weather in May »

June ushers in the start of summer in Pennsylvania, transforming the state's climate to one that is both warmer and more humid. The temperature spectrum typically spans from 57°F (13.9°C) to 77°F (25°C), though on certain days, especially towards the month's end, it can rise even higher. Weather in June »

July stands as the zenith of summer in Pennsylvania, presenting both the warmest temperatures and the pinnacle of outdoor activities. The state's temperature generally fluctuates from 62°F (16.7°C) to 85°F (29.4°C), although on the hottest days, it can push closer to the 95°F (35°C) mark. Weather in July »

August in Pennsylvania heralds the closing stages of summer, with a gradual decline in temperatures towards the month's end. Typical readings hover between 60°F (15.6°C) and 82°F (27.8°C). While the month continues to carry the warmth of July, there's an unmistakable hint of the approaching autumn, especially as late August nights start to feel cooler. Rainfall patterns in August are akin to July, marked by intermittent thunderstorms. Weather in August »

As September unfolds in Pennsylvania, it marks the onset of autumn, introducing a refreshing blend of summer warmth and the crispness of fall. Temperatures typically range from 52°F (11.1°C) to 75°F (23.9°C), with the latter part of the month witnessing a more noticeable drop in temperatures. Weather in September »

October is a month of pronounced transformation for Pennsylvania as autumnal shades deepen and temperatures continue their descent. The state typically sees temperatures fluctuating between 40°F (4.4°C) and 65°F (18.3°C), with the colder readings becoming more prevalent as the month advances. Weather in October »

As Pennsylvania moves into November, the state witnesses a tangible shift towards the colder months, signaling winter's impending arrival. Temperatures in November typically settle between 30°F (-1.1°C) and 52°F (11.1°C), with the chill becoming more pronounced as the month progresses. Weather in November »

December ushers in the full force of winter in Pennsylvania, with the landscape often blanketed in snow and temperatures dipping to reinforce the season's chilly grip. Temperatures predominantly range from 19°F (-7.2°C) to 40°F (4.4°C), but as the month advances, even colder conditions prevail, particularly during nighttime. Snowfall becomes a more common occurrence, with the state's mountainous regions and areas near Lake Erie receiving a significant portion. Weather in December »