Route 66 by Motorcycle: Complete Weather Guide from Chicago to LA

Route 66 is the most iconic motorcycle journey in the United States — and one of the most meteorologically challenging. Covering approximately 3,940 km from Chicago, Illinois to Santa Monica, California, the Mother Road threads through eight states, four distinct climate zones, and a staggering range of weather extremes. Desert heat that buckles asphalt, tornado-spawning supercells, monsoon flash floods, and bitter Midwest winters all feature on this route at the wrong time of year. Getting the timing right is everything.

Route Overview

The original Route 66 — marked today by a combination of the original road, historic bypasses, and the Interstate system — passes through Illinois, Missouri, Kansas, Oklahoma, Texas, New Mexico, Arizona, and California. No two consecutive days of riding feel climatically the same.

Distance: ~3,940 km (Chicago to Santa Monica)
Estimated riding time: 14–21 days at a relaxed pace with sightseeing stops
States crossed: Illinois, Missouri, Kansas, Oklahoma, Texas, New Mexico, Arizona, California
Maximum notable altitude: Continental Divide in New Mexico (~2,400 m); Flagstaff, Arizona (~2,100 m)
Surface: Mostly paved; original sections may be rough asphalt or unmaintained

Weather Patterns by Section

Illinois and Missouri (Chicago to Springfield to St. Louis)

The route begins in the humid continental climate of the Midwest. Summers are warm and humid, with temperatures regularly reaching 30–35 °C in July and August, accompanied by high dewpoints that make riding feel significantly hotter. Spring and summer bring frequent afternoon thunderstorms — often severe — with lightning, hail, and brief but intense downpours. Winters are genuinely harsh: temperatures fall well below freezing from December through February, and ice on the road makes riding extremely dangerous. Spring (April–May) is the most dynamic weather season: warm enough to ride but susceptible to rapid weather changes.

Oklahoma and the Texas Panhandle (Through Tulsa and Amarillo)

This is Tornado Alley, and it earns the name. From April through June, the collision of warm moist air from the Gulf of Mexico and cold dry air from the Rockies generates supercell thunderstorms capable of producing large tornadoes. Amarillo, Texas sits at the heart of one of the highest tornado-frequency zones in the world. Riding through this section during peak season without monitoring the National Weather Service (NWS) storm alerts is genuinely reckless. Tornadoes can develop in under 30 minutes. Summers outside tornado season are brutally hot — Amarillo regularly hits 38–42 °C in July — with very little shade or shelter on the open plains. Crosswinds on exposed stretches of the panhandle can exceed 60–70 km/h on ordinary days.

New Mexico and Northern Arizona (Albuquerque to Flagstaff)

The route climbs dramatically into the high desert. Albuquerque sits at 1,600 m and Flagstaff at 2,100 m, meaning temperatures are significantly cooler than you might expect: Flagstaff averages only 27 °C in July and can drop to 5–8 °C at night even in midsummer. The desert's surprise is how cold it gets after dark.

From July through September, the North American Monsoon brings dramatic afternoon thunderstorms across New Mexico and Arizona. These storms build fast, drop heavy rain on baked desert ground, and generate flash floods in dry washes (arroyos) that can fill with fast-moving water in minutes — even when skies directly overhead are clear. A cloudburst 30 km away can send a wall of water through a desert ravine with no warning. Never camp in or near dry riverbeds during monsoon season. Heed all road closure signs — they exist because riders and drivers have died ignoring them.

California: Mojave Desert to Santa Monica

From Needles, California — one of the hottest inhabited places in North America — the route crosses the Mojave Desert. Summer temperatures here routinely reach 43–47 °C, and road surface temperatures can exceed 70 °C, significantly affecting tyre pressure and grip. Carry and drink water constantly: a minimum of 4 litres per riding hour in peak heat. The final descent from the high desert towards the Los Angeles Basin brings a welcome climatic shift — the marine layer moderates temperatures, and by the time you reach Santa Monica the air is 10–15 °C cooler than the desert interior. The Pacific Coast is your reward.

Key Weather Risks for Motorcyclists

Tornado season in Oklahoma and Texas (April–June) — This is a genuine safety risk, not just discomfort. Download a storm-tracking app (RadarScope is widely used by storm chasers), monitor NWS watches and warnings actively, and have a plan to shelter in a solid building — not under a bridge — if a tornado warning is issued for your area.
Extreme desert heat (June–September) — Heat stroke and dehydration are real dangers. Tyres can overheat and lose pressure. Schedule desert crossings for early morning (before 9:00 am) and shelter during midday. Check tyre pressure when the tyres are cold, as heat expansion can give false high readings.
Monsoon flash floods in Arizona and New Mexico (July–September) — Check NMDOT (New Mexico Department of Transportation) and AzDOT (Arizona Department of Transportation) for flood warnings before riding. If a road shows signs of recent water flow across it, wait. The debris left by flash floods can also puncture tyres.
Plains thunderstorms and lightning — On the open Midwest and Oklahoma plains there is nowhere to shelter. Lightning strikes motorcyclists at greater risk than enclosed vehicle occupants. When a storm approaches, get off the bike and find a building or low ground away from trees and exposed ridges.
Winter ice in Illinois and Missouri (December–February) — Black ice forms rapidly on bridges and underpasses. Route 66 effectively becomes inadvisable for motorcycle travel during this window.

Best Time to Ride

September and October is the optimal window for most riders. The summer heat has broken across the desert, tornado season is over, the Midwest autumn colours are spectacular, and daytime temperatures across all sections are moderate and pleasant — typically 18–28 °C. Days are still long enough for comfortable mileage and the tourist crowds of summer have thinned.

May is the second-best option — warm enough across the northern sections, the desert is not yet at full summer ferocity (though temperatures in the Mojave can already reach 38–40 °C in late May), and the landscapes are often green from spring rains. The caveat is tornado risk in Oklahoma and Kansas: if you ride in May, monitor weather actively through the panhandle and do not ride into storm-warned areas.

Avoid July and August unless you are experienced in extreme heat riding and plan your desert crossings meticulously. Avoid December through February in the Midwest.

Tips for Smart Route Planning

Download RadarScope or a similar storm-tracking app and learn to read it before you enter tornado country. The NWS also offers free severe weather push alerts — turn them on.
Do not ride through Oklahoma and Kansas if a tornado watch is in effect for your route counties. Pull over, eat a meal, wait it out. A watch means conditions are favourable for tornado development; a warning means a tornado has been detected. In a warning, seek immediate solid shelter.
Carry a minimum of 4 litres of water per person when crossing the Mojave or New Mexico high desert in summer. Add electrolyte tablets — sweating heavily through riding gear depletes salts, not just water.
Check NMDOT and AzDOT daily during monsoon season (July–September) for road closures due to flash flooding. Many of these closures lift within hours once water recedes, but attempting a flooded crossing on a motorcycle is extremely dangerous.
Plan your desert riding around the clock. Start before sunrise, ride until 10:00–11:00 am, rest in air conditioning during peak heat (12:00–16:00), then ride again in late afternoon into evening.
Check fuel range carefully through the Texas and New Mexico sections. Some original Route 66 alignments pass through very small towns where historic gas stations are now closed museums. Always fill up before entering long rural stretches.
Route Forecast's elevation profile overlaid with weather is invaluable across the 3,940 km of Route 66's altitude variation — from the flat Illinois plains to the 2,400m Continental Divide crossing and back down to the Mojave — because temperature, storm risk and tyre conditions all shift dramatically with elevation changes that aren't obvious on a flat map. Export the forecast as an image and share it with your riding party before each day's section; on a route this long, coordinating weather awareness across the group keeps everyone making the same go/no-go decisions.

Before you head out, use Route Forecast to check the point-by-point weather forecast for the entire route. Wind, rain and temperature at every kilometre, in real time — overlaid on the full elevation profile so you see exactly where weather changes meet each climb and descent. Export the forecast as an image to share with your group before departure.