Dee Why flood map & planning overlays
A planning-constraint profile of Dee Why
(Northern Beaches, NSW) - 3.4 km², mapped from live council and
state overlay data. This suburb is moderately constrained.
Profile updated 3 October 2026.
Suburb-wide figures; the free map shows which overlays touch your lot.
Constraint readout
3.4 km² - this suburb is moderately constrained by planning overlays.
Elevation hillshade with street names, clipped to Dee Why's boundary, with the flood, bushfire and environmental overlays drawn on top. Magenta is where aircraft were observed in the sampled period, brightest below 3,000 ft.
Nearby suburbs, nearest first
Aircraft noise and flight paths over Dee Why
Two different things, kept apart on purpose. The ANEF contour is the planning instrument - a forecast published per airport that planning schemes use to control noise-sensitive development. Observed overflight is what a sampled aircraft-tracking feed actually recorded over the suburb - where aircraft flew, how low and how often.
Observed overflight - sampled 4 Sep to 2 Oct 2026
typical observed square 2 a day
Night movements: not established - night is sampled as often as day, but too few night flights have been seen here to conclude either way.
Traffic is sampled rather than watched continuously, so every figure is a floor: aircraft not captured between samples are not represented. Rates are per 500 m square - the busiest square in the suburb, not a count of flights over the suburb - and a square is only rated where enough traffic was seen to measure it. Altitudes are above mean sea level. Flight paths change with runway use, weather, season and airspace design. This is a record of observed traffic; it is not a noise contour and not a planning control.
Dee Why at a glance
How Dee Why is zoned
Buying in Dee Why? The zoning, flood and bushfire lines on the section 10.7 certificate attached to the contract are mapped controls - see our s10.7 certificate guide.
Across its 3.4 km², Dee Why is moderately constrained by planning overlays. About 28% of the suburb sits within a mapped flood overlay, and 10% is flagged bushfire-prone. There are 20 heritage-listed sites on record, and the dominant land-use zone is Low Density Residential. The median lot measures about 650 m² across 2,487 parcels.
Who lives in Dee Why
Census 2021 figures published by the ABS for the Dee Why suburb boundary itself, not a wider region.
Socio-economic standing
ABS SEIFA 2021 ranks every Australian suburb. Decile 1 is the most disadvantaged tenth of the country, decile 10 the least.
Score 1071, and decile 9 within New South Wales. The national average is 1000.
Age profile
Share of Dee Why's 23,354 residents in each ABS age band.
Population trend, 2001 to 2025
Estimated resident population of Dee Why - North, the wider ABS statistical area containing Dee Why. There is no annual population series published at suburb level, so this describes the surrounding area rather than Dee Why itself.
11,772 in 2001 to 19,332 in 2025, up 64%.
Source: ABS Census 2021 and SEIFA 2021 (Suburbs and Localities), Regional Population (SA2), CC BY 4.0. Small counts are randomly adjusted by the ABS.
Dee Why data sources and coverage
“Not mapped” means we hold no source layer for this suburb - never an all-clear.
| Dataset | Coverage | Publisher |
|---|---|---|
| Flood mapping | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Bushfire-prone mapping | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Zoning | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Heritage and environment | Mapped where published | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Aircraft noise contours (ANEF) | Not held | NSW Government spatial services, NSW ePlanning and published council flood studies, Defence |
| Observed flight paths | Observed | adsb.lol, under the Open Database License |
| Demographics | Available | Australian Bureau of Statistics (2021 Census and SEIFA) |
Profile last materially updated 3 October 2026. See the methodology and full source list. Source data changes over time and critical decisions should be checked with the responsible authority.
Check a specific Dee Why address
See exactly which overlays touch a single property - the interactive map is free. Need it on paper? A full planning PDF is just $9.
Aircraft have been seen below 3,000 ft over about 91% of Dee Why. The report's Aircraft Overflight page narrows that to the address itself: how many aircraft a day, how low, and at what heights.
Published flood models are held over parts of Dee Why. The free check tells you whether one reaches an address; where it does, a Flood Model Report is +$9 with the planning report.
Building or pricing a slab? The $119 geotechnical desktop report covers geology, soils, bores and an indicative AS 2870 site class for a Dee Why lot.
See what's in the $9 report →Dee Why planning - frequently asked
Is Dee Why flood-prone?
About 28% of Dee Why falls within a mapped flood overlay, against the council-wide suburb average of 12%. Published flood models are held over parts of Dee Why; the free check on the Flood Model Report page says whether one reaches a given address.
Is Dee Why bushfire-prone?
Around 10% of Dee Why is mapped as bushfire-prone, compared with a Northern Beaches average of 47%.
Is Dee Why under a flight path?
Aircraft were observed below 3,000 ft over about 91% of Dee Why, and over about 98% at any altitude up to 10,000 ft, in the period sampled (4 Sep 2026 to 2 Oct 2026). The lowest measured aircraft was at 500 ft, with an average of 2,000 ft. At the busiest point in the suburb about 5 aircraft a day were recorded passing over one 500 m square. Traffic is sampled rather than watched continuously and flight paths change with runway use, weather and season; the ANEF contour is the planning instrument.
What is the zoning in Dee Why?
The dominant planning zone in Dee Why is Low Density Residential, though the suburb also includes Medium Density Residential and Public Recreation.
Does Dee Why have heritage-listed places?
Dee Why has 20 heritage-listed places on record.
What is the typical lot size in Dee Why?
Across 2,487 surveyed parcels in Dee Why, the median lot size is about 650 m². There are also 14 registered easements mapped in the suburb.
Does Dee Why have a train station?
There is no train station inside Dee Why itself. The suburb is served by 135 bus stops.
What is the population of Dee Why?
At the 2021 Census Dee Why had 23,354 usual residents, with a median age of 36 and an average household size of 2.3 people. The wider Dee Why - North statistical area, which contains Dee Why, went from 11,772 people in 2001 to 19,332 in 2025, up 64%.
Is Dee Why an advantaged suburb?
On the ABS SEIFA 2021 index of relative socio-economic advantage and disadvantage (IRSAD), Dee Why scores 1071 and sits in decile 9 of 10 nationally and decile 9 within New South Wales (decile 1 is the most disadvantaged tenth, decile 10 the least).
What is the median household income in Dee Why?
Median household income in Dee Why was $2,106 a week at the 2021 Census, against $2,778 for the typical suburb in Northern Beaches. Median rent was $550 a week and the median mortgage repayment $2,457 a month.
Compare nearby suburbs
| Nearby suburb | Distance | Flood mapped | Bushfire-prone |
|---|---|---|---|
| North Curl Curl | 1.4 km | 40% | 6% |
| Narraweena | 1.4 km | 10% | 8% |
| Collaroy | 2.0 km | 2% | 23% |
| Curl Curl | 2.1 km | 46% | 0% |
| Brookvale | 2.2 km | 39% | 18% |
| Collaroy Plateau | 2.3 km | 0% | 10% |
| Wheeler Heights | 2.6 km | 8% | 13% |
| Beacon Hill | 2.7 km | 3% | 49% |
| Freshwater | 2.8 km | 10% | 0% |
| Cromer | 3.2 km | 14% | 55% |