Precipitation
Updated 2026-10-29 · todayPrecipitation deficits remain pronounced across the Okanagan. Cumulative precipitation through September 1 was approximately 136 mm in Vernon, 90 mm in Kelowna and 70 mm in Penticton, representing about 55%, 41% and 30% of normal, respectively. The deficit gets worse from north to south and has persisted through the spring and summer, with relatively little precipitation available to offset water use or replenish surface-water and groundwater supplies. The prolonged precipitation deficit is an important underlying driver of the low streamflows, declining lake levels and groundwater stress now being observed throughout the basin.
Stream flows
Updated 2026-10-28 · yesterdayStreamflow conditions continue to reflect severe hydrologic stress across the Okanagan. Many monitored streams transitioned from near- or above-normal conditions earlier in the year to below-normal flows during late spring, with flows remaining depressed through July and August. By late summer, numerous natural streams were within the lowest historical percentile ranges, while many regulated reaches were also substantially below normal. The persistence and geographic extent of these low flows are particularly important because they reduce available aquatic habitat, increase sensitivity to elevated water temperatures, and narrow the margin available to balance environmental flow needs with domestic and agricultural water demands.
Stream temperatures
Updated 2026-10-28 · yesterdayStream temperatures were elevated through much of August, compounding the effects of low flows. At Mission Creek near East Kelowna, water temperatures were above the 19°C general salmonid-stress threshold for much of the month and exceeded the 21°C Okanagan sockeye migration threshold for several days during the warmest period. Temperatures declined sharply toward the end of August, with the most recent observation shown in the report at 17.3°C, providing some short-term relief from acute thermal stress. The cooler conditions are beneficial; however, continued low streamflows mean that aquatic systems remain vulnerable should another period of sustained warm weather occur.
Stream temperature, week by week
Updated 2026-10-28 · yesterdayThe map shows where it was hot on one day; this shows how long it stayed hot, which is what a fish actually experiences. Each cell is one gauge in one week, coloured by that week's average temperature against the two thresholds the deck uses throughout: 19 °C, where salmon and trout start to suffer, and 21 °C, which blocks Okanagan sockeye migration. Read across a row rather than down a column. The Okanagan River mainstem sat in the top band through most of July and August, and 93 gauge-weeks across the basin reached or passed 19 °C this year. It is a weekly average, not a weekly maximum: one hot afternoon would paint a whole week red and overstate the stress.
Net inflow to Okanagan Lake
Updated 2026-10-28 · yesterdayNet inflow provides one of the clearest indications of the magnitude of the 2026 water-supply deficit. The spring freshet was less than half of normal, peaking and ending very early. Weekly net inflow during the late-May period reached only roughly 15,000–17,000 acre-feet, compared with an average freshet peak approaching 50,000 acre-feet per week. Net inflows turned negative and the lake level started dropping by the end of June. In an average year, net inflows turn negative in August. The magnitude of lake drawdown was significantly greater than average.
Lake levels
Updated 2026-10-29 · todayMainstem lake levels remain extremely low for this time of year. As of Oct. 29, 2026, Okanagan Lake was approximately 341.34 m, Kalamalka Lake 390.75 m and Osoyoos Lake 277.69 m. Okanagan Lake is lower than at any point in October in the Water Survey of Canada record, which begins in 1943; the previous October low was 341.39 m in 2003. In early September, Kalamalka Lake reached the lowest level recorded since the installation of its control structures, so low that water could no longer flow into Vernon Creek, a condition known as ‘dead pooling’. The low levels in Okanagan and Kalamalka lakes reflect both the limited water carried into the system by the 2026 freshet and continued summer losses, leaving less stored water available entering the fall and winter recharge period.
Groundwater
Updated 2026-10-28 · yesterdayGroundwater monitoring indicates widespread stress across the region. Most of the observation wells shown in the report are below their historical median for this time of year, with numerous wells in unconfined, confined and bedrock aquifers falling within the lowest historical percentile ranges. Bedrock wells are particularly notable, with most observations concentrated near or below the 10th percentile, while only a small number of monitored wells, primarily in unconfined aquifers, remain near or above normal. The broad distribution of low groundwater levels indicates that drought impacts are not limited to surface-water systems and may also affect groundwater-dependent water supplies and groundwater contributions to stream baseflow.
Groundwater, week by week
Updated 2026-10-28 · yesterdayThe chart above shows where groundwater sits today; this shows how long it has been there, which for an aquifer is the more important question. Each cell is one well in one week, scored against that well's own record for the same time of year, using the same classifier the ok.gw tool uses. The reference excludes 2026 on purpose: a drought year that helped set the standard it is judged against would read less extreme than it is. Read across a row and the pattern is stark. Most wells crossed into below-normal in April and May and have stayed there, and 17 of the 28 reporting wells are much below normal this week.
Seasonal forecast
Updated 2026-10-01 · 28 days agoThe seasonal temperature outlook does not indicate significant relief from drought pressure. Environment and Climate Change Canada’s September–October–November outlook shows a 64% probability of above-normal temperatures for the Okanagan, compared with a 27% probability of near-normal and only a 9% probability of below-normal temperatures. Warmer fall temperatures can prolong evapotranspiration and outdoor water demand and may delay the seasonal reduction in water losses normally associated with cooler autumn conditions. Substantial and sustained precipitation would therefore be required to materially improve the basin’s hydrologic position heading into winter.
How water moves through the Okanagan
Fixed reference · long-term averageThis is the Okanagan Lake watershed, from the mountain tops down to the dam at Penticton. Think of it as a very large, very slow bathtub, kept in two accounts that each add to 100%. The first is the watershed. Of all the rain and snow that falls on it in an average year, about 80% goes straight back into the air, because trees, grass and orchards drink it and breathe it out again. About 13% runs off into creeks and about 7% soaks into groundwater. About 14% of the rain and snow reaches Okanagan Lake: the 13% in creeks, less about 2% pumped from creeks, upland reservoirs and wells on the way, plus about 3% from rain falling on the lake and groundwater seeping in. That last 3% is worked out by difference, because groundwater flowing into the lake has never been measured. The second account is the lake itself, and it counts everything that arrives in Okanagan Lake as 100%. From there it leaves three ways. The sun lifts about 40% straight off the surface. About 57% is released at Penticton Dam, by far the biggest outflow and the one we have the least freedom over, because fish, farms and communities downstream depend on it. We pump about 5% out for homes, farms and businesses and give about 2% back as treated wastewater, so about 3% is really ours to keep. The tap looks tiny next to the dam, and in the lake it is. But the lake is not where most of our water comes from. Basin-wide use is close to six times what is drawn from Okanagan Lake, because most of it is taken from creeks, upland reservoirs and wells higher up. The figure people quote for lake extraction always understates what the valley actually uses. The last thing this graphic shows is the slowest one. Only about 1.7% of the lake's volume is replaced in any year, so the lake is not a tank that refills each spring. It is a bank balance drawn down over a run of dry years and paid back over a run of wet ones. Every share above is a long-term average, and the graphic says plainly that averages are not a forecast: inflow, evaporation and demand all swing hard from year to year, and a run of dry years like 2022 to 2026 takes the lake down faster than an average year puts back.
Notes, sources and variability
Fixed reference · long-term averageThe graphic above cites five numbered notes, and this is where they live. They matter more than notes usually do, because several of the headline values are worked out ON the graphic rather than read from a study: the precipitation total and the return to the atmosphere are back-calculated from tributary streamflow, the lake inflow is derived from the outflow terms, and the water pumped above the lake is an estimate assembled by subtraction. The notes say exactly how each was reached, what is measured and what is not, and where the numbers came from. Open it full size to read it.