Last updated: August 27, 2025
In Grimstad, Norway, September presents a blend of mild temperatures and notable rainfall. The maximum temperature reaches a comfortable 25°C (77°F), while the average hovers around a cool 14°C (57°F), and the nights can dip to a brisk 4°C (40°F). With a precipitation total of 115 mm (4.5 in) spread over 14 days, residents and visitors can expect a damp month, accentuated by a high humidity level of 86%. This combination makes September a transitional period, showcasing the shift from the warmth of summer to the crispness of autumn in this picturesque coastal town.
In September, Grimstad, Norway, experiences a gentle transition from the warmth of summer to the crispness of autumn. The temperatures range from a mild 4°C (40°F) at night to a comfortable 25°C (77°F) during the day, offering a pleasant average of 14°C (57°F). This month marks a noticeable shift, showcasing cooler evenings compared to the balmy summer nights of August. As September progresses, the days still invite outdoor exploration while hinting at the beautiful fall colors to come, making it a delightful time for visitors to enjoy the charming coastal town before winter approaches.
In Grimstad, Norway, September marks a notable increase in precipitation, with rainfall totaling 115 mm (4.5 in) over 14 days—the highest monthly figure since June. This surge in rain sets the stage for autumn, signaling a transition from the comparatively drier days of summer. The intensity of September's showers, combined with a gradual rise in precipitation days, further distinguishes it as the precursor to the wetter months ahead. As the landscape embraces the inviting hues of fall, residents and visitors can expect the rhythmic patter of rain to become a familiar sound, hinting at the even greater rainfall that October and November are poised to deliver.
In September, Grimstad experiences a notable shift in humidity, with levels rising to 86% after the summer months. This transitional period sees a significant increase from the 74% recorded in July and 78% in August, signaling the approach of autumn. The humidity remains relatively high compared to spring, where levels hovered around 75% in May and 83% in April. Interestingly, September's humidity prepares the region for the more pronounced dampness of October, which returns to a high of 92%. This consistent pattern hints at a defining characteristic of Grimstad's climate— a year-round inclination towards moisture, particularly pronounced as winter draws near.
In September, Grimstad's UV Index dips to 4, placing it in the moderate exposure category, which means that while sun protection is still advisable, it's not as critical as in the sunnier months. This transition reflects a gradual decline from the high indexes of summer, particularly July and August, when the UV levels peaked at 7. As the days become shorter and the air cooler, your burn time extends to 30 minutes, allowing for more leisurely outdoor activities without immediate risks. As we move into the fall months, individuals should remain mindful of UV exposure, especially during peak hours. For more insights on UV levels throughout the year, check out the Grimstad UV Index.
UV Risk Categories
As September settles over Grimstad, Norway, the days are bathed in a gentle glow, offering 289 hours of sunshine—a radiant farewell to the summer warmth. This month marks a soft transition from the sun-drenched heights of July's 475 hours and August's 410 hours. Though daylight begins to wane, September's brightness still lingers, providing a beautiful contrast to the swiftly darkening days that follow in October. The trend reveals a strong summer peak, slowly diminishing towards the winter months, where the sun's presence diminishes dramatically, falling to just 98 hours in December. Thus, September stands as a delightful bridge, where lingering sunny days invite residents to savor the last tastes of outdoor warmth before embracing the cooler, quieter months ahead.
In Grimstad, Norway, the chances of enjoying sunny weather in September drop to 31%, marking a noticeable decline from the peak sunshine months of April and August, which see probabilities of 66% and 49% respectively. Following a relatively bright summer, where July and August hover close to the 50% mark, September ushers in the onset of autumn, bringing a shift towards cloudier skies. As the days shorten and temperatures cool, individuals hoping for sun must temper their expectations. Despite this dip, September still offers more sunny spells than the bleak winter months ahead, making it a transitional period for those who appreciate the changing seasons.
As summer fades, September in Grimstad, Norway, marks a gradual shift toward shorter days, offering about 12 hours of daylight. After basking in nearly 18 hours in the peak of June, the daylight begins its steady decline, foreshadowing the deepening darkness of autumn and winter. The transition from the bright, joyful days of summer to the cooler, softer lights of early autumn is palpable, as the city prepares for the coming months. The daylight duration remains inviting but starts to recede, creating a serene atmosphere perfect for cozy activities and enjoying the fading warmth of the season.
As September arrives in Grimstad, Norway, the winds begin to pick up slightly, with an average speed of 4.6 m/s (10 mph). This marks a subtle increase compared to the calmer summer months, where winds averaged around 4.0 m/s (9 mph) in both July and August. Interestingly, September's breezes set the stage for the transitioning seasons, as the wind speeds start to rise again, foreshadowing the more vigorous gusts of October, which see a jump to 5.6 m/s (12 mph). Overall, this month acts as a bridge, with its wind patterns hinting at the approaching autumn while still holding onto the remnants of summer's gentler touch.
Weather in Grimstad varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Grimstad, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present contrasting weather patterns in terms of temperature, precipitation, and humidity. In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 25°C (77°F), with an average of 14°C (57°F). The month experiences significant rainfall, totaling 115 mm (4.5 in) over 14 days, accompanied by a humidity level of 86%. In stark contrast, January sees much colder conditions, with temperatures dropping to a minimum of -11°C (12°F) and only reaching a maximum of 10°C (49°F), resulting in an average temperature of just 2°C (36°F). Precipitation in January is lower at 81 mm (3.2 in) over 12 days, and humidity levels rise slightly to 93%. For more detailed information about the weather in January, you can visit Grimstad weather in January.
September and February present contrasting weather patterns. In September, temperatures range from a mild minimum of 4°C (40°F) to a pleasant maximum of 25°C (77°F), with an average of 14°C (57°F). The month sees approximately 115 mm (4.5 in) of precipitation spread over 14 days, coupled with a high humidity level of 86%. In stark contrast, February experiences chillier conditions, with temperatures dipping as low as -12°C (10°F) and averaging only 2°C (35°F), reaching a maximum of 10°C (51°F). The precipitation during February is slightly lower at 103 mm (4.0 in) over 13 days but comes with an even higher humidity of 91%. For a more detailed look at February weather, visit Grimstad weather in February.
When comparing the weather in September and March, notable differences emerge. September offers a milder climate, with temperatures ranging from a minimum of 4°C (40°F) to a comfortable maximum of 25°C (77°F), along with an average temperature of 14°C (57°F). It experiences 115 mm (4.5 in) of precipitation over 14 days, contributing to a relatively high humidity of 86%. In contrast, March is much cooler, featuring temperatures that drop to a minimum of -10°C (14°F) and peak at 17°C (64°F), resulting in an average of just 3°C (38°F). The month also sees slightly less precipitation at 97 mm (3.8 in) over 12 days, albeit with humidity remaining high at 88%. For more details about the weather in Grimstad during this month, check out Grimstad weather in March.
September and April present contrasting weather conditions. In September, temperatures range from a minimum of 4°C (40°F) to a pleasant maximum of 25°C (77°F), with an average of 14°C (57°F). The month experiences relatively high precipitation of 115 mm (4.5 in) over about 14 days, accompanied by humidity levels around 86%. In contrast, April features cooler temperatures, with a low of -5°C (23°F) and a maximum of 17°C (62°F), averaging 6°C (44°F). Precipitation is significantly lower at 38 mm (1.5 in) over just 6 rainy days, and humidity is slightly lower at 83%. To learn more about April weather specifics, you can visit Grimstad weather in April.
When comparing the weather in September and May, we can observe notable differences. September features a wider temperature range, with minimums around 4°C (40°F) and maximums peaking at 25°C (77°F), resulting in an average temperature of 14°C (57°F). In contrast, May presents slightly cooler conditions, with minimums at 1°C (34°F) and an average temperature of 11°C (52°F), while still reaching similar maximums of 25°C (78°F).
Precipitation levels also vary, with September experiencing higher rainfall at 115 mm (4.5 in) over 14 days compared to May's 83 mm (3.3 in) over 10 days. Additionally, September tends to be more humid, averaging 86% humidity, whereas May has a more comfortable 75%. For a closer look at May's weather specifics, you can check out Grimstad weather in May.
In comparing the weather of September and June, we see notable differences in temperature and humidity levels. September experiences a wider temperature range, with minimums around 4°C (40°F) and maximums reaching up to 25°C (77°F), while June is slightly warmer, with minimums of 6°C (43°F) and maximums peaking at 28°C (83°F). Additionally, September tends to be wetter, accumulating about 115 mm (4.5 inches) of precipitation over 14 days, compared to June's 88 mm (3.5 inches) over 11 days. Humidity levels are also higher in September at 86%, compared to June's 74%, making September feel more damp overall. For a closer look at the specific conditions in June, you can visit Grimstad weather in June.
In comparing the weather between September and July, we see notable differences in temperature, precipitation, and humidity. September experiences cooler temperatures, with a minimum of 4°C (40°F) and an average high of 25°C (77°F), while July features milder conditions, with a minimum of 9°C (49°F) and an average maximum of 27°C (81°F). Precipitation is higher in September, totaling 115 mm (4.5 in) over 14 days, compared to July's 88 mm (3.5 in) over 11 days. Additionally, September has a higher humidity level at 86%, compared to July's more comfortable 74%. For more details on July weather specifics, you can visit Grimstad weather in July.
In comparing the weather between September and August, September tends to be cooler with minimum temperatures dropping to 4°C (40°F) compared to August's minimum of 9°C (48°F). Despite having the same maximum temperature of 25°C (77°F), September's average temperature is slightly lower at 14°C (57°F) versus August's 16°C (62°F). Precipitation is slightly higher in September, totaling 115 mm (4.5 in) over 14 days, whereas August sees 101 mm (4.0 in) over 13 days. Furthermore, humidity is noticeably higher in September at 86%, compared to August's 78%. For more details, check out Grimstad weather in August.
September and October exhibit notable changes in weather, marking the transition from late summer to autumn. In September, temperatures range from a minimum of 4°C (40°F) to a maximum of 25°C (77°F), with an average of 14°C (57°F), and the month experiences a total precipitation of 115 mm (4.5 in) over 14 days. By contrast, October sees cooler temperatures, with lows dropping to 0°C (32°F) and a high of only 17°C (62°F), averaging around 10°C (50°F). Additionally, October is wetter, with 169 mm (6.7 in) of precipitation spread across 15 days, and humidity rises slightly to 92%. For more detailed insights on the weather patterns, check out Grimstad weather in October.
September and November present distinct shifts in weather patterns. In September, temperatures range from a mild 4°C (40°F) at night to a comfortable average of 14°C (57°F) during the day, with maximum highs reaching 25°C (77°F). This month typically sees 115 mm (4.5 in) of precipitation over 14 days and maintains a relatively high humidity of 86%. In contrast, November brings a noticeable drop in temperatures, with nighttime lows falling to -6°C (22°F) and an average of just 6°C (43°F) during the day, peaking at 14°C (58°F). Rainfall increases slightly to 128 mm (5.1 in) over 16 days, while humidity also rises to 92%. For more details about November weather, visit Grimstad weather in November.
In September, temperatures in Grimstad range from a minimum of 4°C (40°F) to a maximum of 25°C (77°F), with an average of 14°C (57°F). The month experiences moderate rainfall totaling 115 mm (4.5 in) over approximately 14 days, coupled with a relatively high humidity level of 86%.
In contrast, December brings much colder conditions, with temperatures dipping from a minimum of -9°C (15°F) to a maximum of 11°C (53°F) and an average of just 3°C (38°F). Precipitation increases to 152 mm (6.0 in) spread over 19 days, while humidity rises slightly to 92%. The shift from the warm, wet weather of September to the chilly, damp winter of December is quite striking. For more detailed information, check Grimstad weather in December.
As summer fades, September in Grimstad brings a notable shift in weather patterns. With a cooler average temperature and increased humidity levels, this month often feels more brisk compared to the warmer months of July and August. The higher frequency of rainfall, experiencing about half the month with precipitation, sets the tone for the transitioning season. While the days can still be pleasantly warm, the contrast with colder nights and the unmistakable scent of autumn in the air remind us that winter is on the horizon. For a deeper dive into the local climate trends, check out Grimstad Climate.