Costa Rica's Northern Plains stretch from the base of the Cordillera de Tilarán across fertile lowlands toward the Nicaraguan border, a landscape dominated by the iconic cone of Arenal Volcano and fed by rivers that carve through some of the country's richest rainforest. This is adventure country: you can soak in volcanically heated hot springs along the Tabacón River, zipline over the canopy, float past sloths and howler monkeys on the Peñas Blancas, hike to the surreal sky-blue waterfall at Río Celeste, and explore the underground chambers of the Venado Caves. La Fortuna, the region's gateway town, anchors it all with a compact center full of tour operators, local sodas serving gallo pinto and tilapia casados, and volcano views from nearly every angle.
The ideal window for visiting the Northern Plains runs from late October through mid-April, covering the dry season when trails are firm, volcano views are clearest, and Lake Arenal's trade winds draw windsurfers from around the world. Within this range, November through March delivers the most consistently dry weather, with rain chances below 10% from January through March and humidity at its lowest. If you prefer thinner crowds and lower accommodation rates, November and early December offer nearly the same dry conditions with fewer visitors than the peak months of January and March. A secondary window opens briefly in late June through late July, except for a couple of stretches in early and mid-July when conditions can dip, giving you warm weather and green-season pricing if you don't mind occasional afternoon showers. Late August also offers a short viable window around mid-month.
Spring in Northern Plains, Costa Rica
March is one of the driest months in the Northern Plains, with only about a 2% chance of significant rain on any given day, making it one of the best stretches for hiking Arenal Volcano National Park's lava trails or tackling the 480-step descent to La Fortuna Waterfall without muddy footing. Mornings start mild with lows near 66°F (18.9°C), warming to afternoon highs around 82.8°F (28.2°C), comfortable enough for a full day of canopy tours and hanging bridges walks at Mistico Park. The annual livestock show in the community of Platanar de Florencia typically falls in April, complete with traditional horse parades known as topes, concerts, and a showcase of the region's agricultural heritage.
Late April brings the year's peak heat, with highs reaching 84.2°F (29°C) and lows holding at 66.6°F (19.2°C). By May, rain chances climb to around 31%, and afternoon showers become a regular occurrence, turning the landscape an even deeper green. This is the second busiest tourist season overall, so expect moderate crowds at popular spots like the Tabacón hot springs and Río Celeste, especially during Easter week. Juan Santamaría Day in mid-April is a national holiday that can bring domestic travelers to the region, and some businesses may close briefly.
Pack layers for early mornings and a reliable rain jacket from mid-April onward. Lightweight hiking shoes with good tread will serve you well on both dry lava rock and increasingly damp forest trails as the season progresses.
Summer in Northern Plains, Costa Rica
The Northern Plains shift fully into green season from June through August, and the rainforest earns its name. Afternoon showers roll through regularly, with rain chances hovering between 28% and 36% across these months. Rivers run high, making this an excellent time for whitewater rafting on the Sarapiquí and Balsa rivers, and wildlife activity picks up as the forest comes alive. A safari float down the Peñas Blancas River in the morning, before the clouds build, gives you strong odds of spotting monkeys, sloths, and basilisk lizards along the banks.
Highs average 82.1°F (27.8°C) with lows around 66.6°F (19.3°C), so temperatures remain pleasant even as humidity climbs into the low 60% range. Tourism drops noticeably, making this the quietest stretch outside of fall, and accommodations are priced accordingly. The late July holiday celebrating the Annexation of Nicoya sometimes brings local festivities and a bump in domestic tourism. Arenal Volcano is more likely to be shrouded in cloud during the afternoons, so set your alarm early if a clear volcano view matters to you.
Waterproof everything: a quality rain jacket, dry bags for electronics, and shoes that can handle mud are essentials. Chocolate tours through local cacao plantations and spelunking in the Venado Caves are smart rainy-day alternatives when the trails get soggy.
Fall in Northern Plains, Costa Rica
September is the wettest month in the Northern Plains, with roughly a 55% chance of significant rain on any given day. Trails can be slippery, river levels run at their highest, and Arenal's summit often hides behind thick cloud cover for most of the day. This is also the least busy period for tourism, with visitor numbers dropping to less than half of peak season levels. If you're comfortable with rain, the trade-off is genuine solitude at popular spots and the lowest accommodation rates of the year.
Temperatures remain mild and steady through fall, with highs averaging 81.6°F (27.6°C) and lows near 65°F (18.3°C). The Caño Negro Wildlife Refuge, a spectacular wetland preserve about 90 minutes from La Fortuna, is especially rewarding during the wetter months when migratory birds arrive and the waterways teem with herons, kingfishers, and the occasional roseate spoonbill. Costa Rica's Independence Day falls in mid-September, and you may catch parades and community celebrations in the smaller towns across the region. By late October, rainfall drops sharply, and the transition toward dry season begins in earnest.
Bring waterproof boots and a packable rain shell for this season. Insect repellent is more important now than at any other time of year, as standing water from heavy rains creates prime mosquito habitat.
Winter in Northern Plains, Costa Rica
December through February is when the Northern Plains are at their most accessible and dramatic. Rain chances plummet to between 0% and 9%, January often passes without a single significant rainy day, and the dry conditions mean volcano views are the clearest they'll be all year. This is prime season for hiking the old lava flows on the Arenal 1968 Trail, where the stark contrast between barren volcanic rock and dense green forest is striking under blue skies. The trade winds pick up across Lake Arenal during these months, regularly exceeding 20 knots and drawing windsurfers and kiteboarders from around the world.
Highs average a comfortable 80.1°F (26.7°C) with lows around 65.2°F (18.4°C), and humidity sits at its lowest, near 47% in February. Breezy conditions make afternoons on the lake feel refreshingly cool, though January's sustained winds can reach about 13.8 mph, adding a chill if you're on the water. Army Abolition Day in early December and the Christmas and New Year holidays bring a surge of both international and domestic visitors, and this is the busiest tourism period of the year. Booking accommodations and popular tours well in advance is essential.
Evenings can feel surprisingly cool after a windy day at elevation, so pack a light fleece alongside your warm-weather gear. The dry trails and low humidity make this the best stretch for tackling longer hikes, like the climb up Cerro Chato to its emerald crater lake or the 7-kilometer loop through Tenorio Volcano National Park to see Río Celeste at its most vivid.
At a Glance
Monthly weather, visitor crowds, air quality, holidays, and daylight hours to help you plan your trip.
Travel Tips & Safety for Northern Plains, Costa Rica
La Fortuna sits roughly 2.5 hours from both San José's Juan Santamaría International Airport and Liberia's Daniel Oduber Airport in Guanacaste. Renting a car gives you the most flexibility for reaching Lake Arenal, Río Celeste, and the Venado Caves, and the main roads to La Fortuna are mostly paved. Shared shuttle services also run daily between major tourist hubs, and a popular taxi-boat-taxi route connects La Fortuna with Monteverde if you want to combine both regions. Tipping in Costa Rica typically runs around 10%, and many restaurants include a service charge on the bill already.
Petty theft, particularly pickpocketing and car break-ins, is the most common concern for visitors. Keep valuables out of sight in parked vehicles, use hotel safes, and stay alert in crowded areas. The roads around the Northern Plains can be narrow with limited lighting after dark, so plan to finish any driving before sunset when possible. Tap water is generally safe to drink throughout Costa Rica, but confirm with your lodging in more rural areas.