Climate FAQs

Weather refers to the current conditions of our atmosphere (i.e., sunny, cloudy, warm, cold, raining, snowing, etc.) as well as the short-term changes in those conditions. Climate is the average weather over a long period of time, as well as how “extreme” the conditions can get for a given location and time period. We typically say that climate is what you expect, but weather is what you get.

Climate normals are the expected conditions for a specific location and time period (day, month, season, etc.) We calculate climate normals by finding the average conditions for a location and time period using many years of data. Typically, we use a 30-year time period to compute climate normals for a location. Currently, we are using the 1991-2020 period as our “normals” period.

Climate normals are how we give a historical context to the current conditions, such as when we say that a day was “wetter than normal” or a month was “warmer than normal.” Updating our climate normals periodically is one way to assess how our climate has changed over time.

State climatology offices do not create forecasts for the day-to-day weather like a TV station or the National Weather Service does. Instead, state climatology offices focus on the long-term patterns in a state’s climate, which include tracking climate normals, extremes, and trends.

Oftentimes, state climatology offices will have data on a state’s climate going back over 100 years! Climatologists at a state climatology office build on the work of forecasting services by providing a historical context to the current and short-term conditions of our atmosphere.

To learn more, read about the Wisconsin State Climatology Office

Wisconsin’s variable weather conditions are primarily a result of the state’s northern location and its distance away from the ocean. Locations in the northern US tend to be colder than southern locations due to less incoming solar radiation at higher latitudes. Also, the oceans tend to suppress day-to-day temperature variations and keep areas nearer to the coasts warmer in the winter and cooler in the summer.

Thus, states like Wisconsin tend to have a larger range between the coldest and warmest conditions in a year and experience more day-to-day variability. The jet stream also brings large-scale weather systems over Wisconsin at all times of the year, which bring everything from severe cold outbreaks in the winter to severe thunderstorms in the summer.

The Great Lakes tend to be cooler than the surrounding land during the summer months, and thus act to keep locations closer to the lakes cooler during the peak heating of summer compared to locations further inland. The opposite effect takes place in winter when the lakes are still unfrozen and are warmer than the surrounding land. Also, if the lakes are unfrozen in winter, lake effect snow can take place along the downwind shoreline as cold air blows over the open water and picks up moisture. This moisture then condenses out as snow once it reaches land.

The hills of Wisconsin do not have the same kind of effect on the weather as the Rocky Mountains, which can create precipitation as air rises up over the mountains. The effect of Wisconsin’s rugged topography, primarily on the western side of the state, tends to be more subtle. Cold air sinks into the valleys at night from higher elevations, which can cause the water vapor in the air to condense into fog in the valley.

Hilltops and valleys might have different land cover and other geographic characteristics (e.g., a body of water in the valley) that will lead to small-scale variations in the conditions between locations. The steepness and land cover of a valley also have impacts on how precipitation enters a river as stormwater runoff, which has implications for flooding.

Urban heat islands occur when highly-developed urban areas are several degrees hotter than less-developed areas nearby. This is a result of a high concentration of man-made materials, such as black rooftops and pavement, that are very efficient at absorbing heat and thus can warm up rapidly on a hot summer day. This creates an environment that is hotter than a less-developed area with more natural land cover that doesn’t heat up as quickly. Remember that the lowest level of our atmosphere (i.e., where we live) is heated from the ground up.

Case study: Summer 2022 Milwaukee Heat Mapping Campaign (Wisconsin DNR)

Although the state is quite a ways away from the Gulf of Mexico, large-scale weather systems in the summer months can bring southerly winds to Wisconsin that contain water vapor from the Gulf (i.e., warm, muggy air). These large-scale systems that bring in Gulf moisture to Wisconsin are the primary reason why summers are humid in the state. It is also basic physics that the atmosphere can contain more water vapor at warmer temperatures.

Growing vegetation adds moisture to the background Gulf moisture through evapotranspiration (evaporation + transpiration), which is loss of water vapor from the plants as they do photosynthesis. In mid-to-late summer, an acre of corn can give off 3,000-5,000 gallons of water per acre in just one day.

• Prior to 1850: U.S. Army Medical Corps began taking systematic weather observations at Fort Crawford (Prairie du Chien, starting in 1820), Fort Howard (Green Bay, 1821), and Fort Winnebago (Portage, 1829).
• 1851-1869: The Smithsonian Institute helped establish a cooperative weather observation network. By 1869, 16 of these stations were operational in Wisconsin. In the early 1850’s, lake ice measurements began on Lakes Mendota and Monona in Madison.
• 1869: Daily weather observations began at UW-Madison (at modern-day Bascom Hall) on January 1, 1869. This station was part of the Smithsonian Institute’s network.
• 1870: The U.S. Army Signal Service was formed, with Milwaukee being the one of 24 inaugural stations that telegraphed weather observations (multiple times per day) to Washington, D.C.
• 1890-1895: The Signal Service’s weather observers, stations, and equipment were transferred from the Department of War to the USDA in 1891 to become the U.S. Weather Bureau (now known as the National Weather Service). As part of the Organic Act of 1890, the Cooperative Observer Network (COOP) was established, which was instrumental in creating a dense observer network across the nation. By 1895, there were 57 COOP stations in Wisconsin.
• Present Day: There are now many observing stations all across the state, which include both human observations (COOP, CoCoRaHS) and automated stations (airports, Wisconet).

To read more about the history of weather observing in the US, check out this history of the National Weather Service and a NOAA article on weather observing.

In climatology, we define an extreme event as weather conditions that are far beyond the average conditions that we expect to experience at a location and time (i.e., a rare event).

Extreme events can be evaluated in two different ways. First, extreme events can be measured by meteorological variables (e.g., precipitation, temperature, humidity, or streamflow) and how long those extreme conditions lasted. For example, a case of extreme rainfall would be a location receiving multiple inches of rainfall in one day when we would only expect a fraction of an inch or less on a “normal” day.

Second, we can define an event as “extreme” based on the impacts to society. By quantifying the impact based on human health impacts, the financial cost of damage to infrastructure, and/or claims filed for assistance, we get a sense for just how damaging an extreme event was to society.

There are several networks of weather monitoring stations across Wisconsin. Here are some examples of these networks and links to view current and past conditions: 

• Automated Surface/Weather Observing Systems (Airports) – interactive map of stations
• NOAA Cooperative Observer Network (COOP) – interactive map of stations
• Community Collaborative Rain, Hail and Snow Network (CoCoRaHS) – map of observations
• Wisconet – map of stations 

Every week (on Thursdays), the National Drought Mitigation Center at the University of Nebraska-Lincoln compiles the latest U.S. Drought Monitor (USDM) map. This map shows the coverage and severity of drought in the U.S., using four categories of drought (moderate, severe, extreme, and exceptional). There are also designations of “normal conditions” as well as “abnormally dry”, which are areas that may be entering or leaving drought status.

The USDM maps are compiled by climatologists, who rely on input from state-level partners (like the State Climatology Office) to provide reports on what is going on at the local level. To make the drought map, physical drought indicators (e.g., streamflow, temperature, soil moisture, etc.) are combined with reports from people around the state who describe the local drought impacts that they are observing.

To explore additional drought and moisture information for Wisconsin, check out the State Climatology Office’s drought website.

Weather apps on your phone, such as from your local TV station, can be great sources for information such as current temperatures, near-term forecasts, and severe weather alerts. However, here are some examples of variables or services that most weather apps do not provide and where you can find this information:

• Drought: Current drought coverage and severity from the United States Drought Monitor (USDM) can be viewed on the USDM’s website.
• River Levels: To view current river levels and forecasts, check out this interactive map from NOAA’s National Water Prediction Service.
• Soil Moisture and Temperature: Wisconet stations across the state are measuring soil moisture and temperature at multiple depths in the ground. You can view current soil conditions for your nearest Wisconet site using the station locator map.
• Ag Weather: If you are a farmer or agronomist and are looking for weather information specific to agriculture, check out the State Climatology Office’s agriculture website. You should also subscribe to get the Ag Weather Outlook for Wisconsin delivered to your inbox.
• Planning Outdoor Activities: Wisconet offers an outdoor activities dashboard that is a one-stop-shop for real-time weather information from Wisconet as well as active weather alerts and a 3-day National Weather Service forecast. All you need to do is set your location!
• Climate Summaries and Outlooks: Weather apps provide lots of real-time information, but how have recent conditions compared to climate normals? The State Climatology Office’s Wisconsin Climate Summaries provide context on how the previous month (or season) compares to averages and past records. Interested in what lies ahead? Weather outlooks for the upcoming month are posted in the Wisconsin Climate Chronicles blog.

Absolutely! Here are a few ways that you can become a part of monitoring Wisconsin’s climate:

• Community Collaborative Rain, Hail and Snow Network (CoCoRaHS) – reporting daily precipitation measurements using a low-cost rain gauge; CoCoRaHS data is used by a wide variety of organizations and individuals.
• Condition Monitoring Observer Reports (CMOR) – reporting on drought conditions in your area that the authors of the US Drought Monitor can reference when updating the drought map.
• Sending the SCO info and/or pictures – link to the SCO feedback form
• Emailing storm impact reports, info, and pictures to your local National Weather Service office

This is a surprisingly hard question. The Wisconsin State Climatology Office has statewide snowfall records dating back to the early 1890s. Based on the raw data, Wisconsin has experienced a noticeable increase in total annual snowfall of around one foot during this period. However, the methods used to measure snowfall have changed significantly over time. For example, observers nowadays are encouraged to take measurements right after a snowfall, whereas observers years ago typically waited until a particular time of day, even though that delay caused some of the snowpack to settle and resulted in lower reported accumulations.

In addition, many older observations used an approximation that the amount of snowfall is 10 times greater than its melted liquid equivalent. So an observer who measured, say, a half inch of melted snowfall would have reported the event as five inches of snow, even though the actual ratio is usually higher. Today’s observers are instructed to directly measure and record the depth of the snowfall on the ground, thus resulting in higher reported snowfalls. The State Climatology Office is assessing Wisconsin’s historical snowfall data to tease out whether our state has truly become snowier over the years.

Since 1950, annual temperatures have been increasing across all of Wisconsin by 3-4°F. Winters have been warming at the highest rate compared to the other seasons, with most in the state experiencing an increase in winter temperatures of 5-6°F. The rate of increase is even higher for winter minimum temperatures (compared to daily maximum temperatures). As a result of warmer winters and autumns, growing season length (frost-free period) has increased at a rate of 2-4 days per decade since 1950 for many in northern and central Wisconsin. Projections from WICCI for mid-century (2041-2060) indicate that the warming trend will continue under moderate emissions. Extreme heat events (e.g., days topping 90°F or nights not dropping below 70°F) are also expected to become more common.

For precipitation, Wisconsin has been getting wetter across all four seasons for most of the state since 1950. The exception to this has been a decreasing precipitation trend in far northern Wisconsin during the summer months. There has also been an increase in the fraction of annual precipitation that falls during heavy rainfall events. WICCI projections indicate that by mid-century, annual precipitation will increase (primarily in winter and spring) and that heavy precipitation events will increase in frequency for most of the state.

One key factor to consider is the relationship between the Arctic and the jet stream. The Arctic is warming faster than the rest of the world, and as it warms, the temperature difference between the Arctic and the equator weakens, which in turn weakens the jet stream. A weaker jet stream can allow for frigid Arctic air to spill southward more easily, leading to more frequent intrusions of cold air in Wisconsin.

On the other hand, because the Arctic air is warming, that could mean that the extreme cold won’t be as bitter as it once was. In fact, we’re already seeing a warming trend in Wisconsin’s annual minimum temperature, as there have been far fewer -40 degree temperatures in recent decades.

Since the mid-20th century, Wisconsin has seen an increase in the frequency and severity of heavy precipitation events. Most of these extreme precipitation events occur during the summer months when thunderstorms with heavy rainfall are most common. Climate projections for Wisconsin indicate that across most of the state, the number of days with heavy precipitation will increase as the climate becomes warmer. As for storms that produce hail, strong winds, or tornadoes, it is harder to assess the changes in those events over time because we are primarily relying on reports from human “storm spotters.” Over time, we have increased the number of spotters and thus the number of reports.

There is not a good one-size-fits-all answer to this question. The answer depends on your lifestyle, livelihood, where you live, and the resources that you have. While the State Climatology Office does not focus on recommending actions to adapt to and mitigate future climate change, here are a few guideposts for you:

• Explore climate data and impacts: Visit the Wisconsin Initiative on Climate Change Impacts (WICCI) website and view key findings from the 2021 report, explore climate trends and projections for Wisconsin, and read or watch outreach material. If you are curious and want to learn more about how future climate modeling works, check out this NOAA article.
• Learn about climate solutions: Ready to give something new a try, or just see what options are available? Resources like Project Drawdown’s climate solutions explorer are a great way to learn about the array of science-based technologies and practices to reduce emissions. Also, consider exploring resources from UW Extension for increasing climate resiliency.
• Find local experts: Don’t feel like you have to face this challenge alone! Find local experts who can help you take action as an individual, community, or business. We encourage you to reach out to your local UW Extension office with questions.
• Be involved: If being prepared for future climate change is something that matters to you and your community, chances are there are groups and initiatives in your area that you can become involved in. Working towards solutions as a collective group is a more effective way to reach goals than acting alone.