Pool season · California
Hawthorne Pool Season: the Year on One Bar
Last updated: July 25, 2026 · dates · water temp
Hawthorne's whole pool calendar, condensed: when the water warms, when it cools, and where today falls between those edges. Use the opening guide and closing guide for the step-by-step work; keep this page for the dates.
Hawthorne, CA — 0 swim days a yearEach dot on the bar is one week of Hawthorne's typical year, colored by what the model says that week is for: gray weeks are off-season, hollow teal marks the opening window (March 8–March 29), solid teal is swim season, and hollow amber is the closing window ending December 2. The black marker is today — its position against the colors is the entire executive summary.
The Hawthorne pool calendar
Opening — target March 15
Target March 15; the practical window runs March 8–March 29, and the 7-day mean crosses the 61°F threshold around March 29. Cold-water starts are the cheap ones.
Closing — deadline December 2
The window opens November 22 once water leaves the algae zone; the model deadline is December 2, a week ahead of the January 5 freeze normal.
Estimated water temperature by month
This is Hawthorne's typical-year water curve: the same EWMA model as the live widget, run on the 1991–2020 normals instead of this week's weather.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 58° | 58° | 60° | 61° | 64° | 66° | 70° | 72° | 72° | 70° | 66° | 59° |
The curve peaks near 72°F — comfortable-water months here usually involve a heater or a solar cover.
Every station tells its own story: compare this curve with Hanford's pool season and Hayward's — neighboring normals stations can shift the windows by a week or more. The full ranking lives on the California season index.
Hawthorne pool season FAQ
When should I open my pool in Hawthorne, CA?
The site model recommends opening by March 15 — about two weeks before Hawthorne's 7-day mean temperature crosses 61°F, while the water is still too cold for algae. The step-by-step sequence is in the Hawthorne opening guide.
When should I close my pool in Hawthorne?
Winterize by December 2. The model holds the deadline a week ahead of Hawthorne's NOAA 50% first-freeze date, so the plumbing is protected before the first hard night. The full sequence is in the Hawthorne closing guide.
How long is the swim season in Hawthorne?
Hawthorne averages 0 days a year with normal highs of 80°F or better — about 17 days earlier than the California median. The California season index ranks all 147 covered cities by the same metric.
How warm does pool water get in Hawthorne?
An unheated pool near Hawthorne typically peaks around 72°F in high summer and bottoms out near 57°F in winter, never quite reaching the 78°F comfort line without a heater or solar cover. The month-by-month curve above shows the whole cycle; the methodology page explains the ±5°F error bars.
Email me when Hawthorne hits the closing window
Data: NOAA 1991–2020 climate normals via Hawthorne Municipal Airport (0.9 mi); live outlook by Open-Meteo. Attribution: sources · assumptions: methodology.