temperatures are generally cooler maximums and warmer overnight minimums than most places in Victoria due to tendency to have:
more wind (even so, overnight temperatures can fall quickly by a few degrees if winds drop below 5kph and of course an Antarctic blast from a severe cold front will produce very cold nights)
more cloud
higher dewpoint
proximity to Bass Strait water body
local Fohn winds with easterlies
the park is one of the windiest areas in Victoria, and being one of the most southern parts of Victoria, it tends to get cooler day time maximum temperatures (summer average high temperatures are around 20degC, with many days hitting 24-28degC) although record summer temperatures have been over 40degC
the Bass Strait sea water temperature (western Bass Strait water temperature peaks in Feb at 18-21degC and falls to a low of 12-14degC in Aug-Sept while the eastern Bass Strait waters are 1-2degC warmer) moderates the lowest temperatures so average overnight minimums in summer tend to be 14-17degC and 9degC in winter although record lows in winter do fall to just below 0degC associated with very cold strong SW/S wind flows from the Antarctic associated with cold fronts.
average overnight minimum temperatures at the lighthouse:
Jan-Mar 14.5degC
April 13degC
May 11degC
June 9.4degC
July-Sept 8-9degC
Oct 10degC
Nov 11degC
Dec 13degC
mean rainfall is much higher May-Oct at around 100mm/mth (rains on 19 days/mth) cf 50mm/mth in Jan-Feb (rains 10 days/mth) while Mar, Apr, Nov, Dec are around 70mm (rains 12-14 day/mth)
cloudiest months are May and June but they tend to be less windy
coolest 3pm mean temperatures at the lighthouse are June-Aug at around 11degC compared with warmest in Feb at 19degC, Tidal River is probably around 1degC warmer in winter and perhaps 2-3deg warmer in summer
beware La Nina and the easterlies
Use of solar panels during easterlies is unlikely to be efficient due to the cloud, while the strong wind gusts can destroy more flimsy designs.
a High pressure system (the higher the pressure, the stronger the winds are likely to be) in the Tasman Sea or centred over Tasmania can send relatively dry strong easterlies into Tidal River which are warmer and drier than usual by not only the eastern Bass Strait water temperatures being warmer, but also the topographic uplift of Mt Latrobe results in a mild Fohn effect creating warmer drier air on the leeward side often with persistent local cloud over Tidal River and converging gusting into Tidal River at around 21degC even overnight in Summer and Autumn, but these strong gusts make camping unpleasant by creating almost inescapable persistent dust bowls of much of the camp ground areas.
strong easterlies also are created by Low pressure systems migrating from the north to be centred just to the north-east of the Prom - the more intense the Low, the stronger the winds are likely to be, and with these, heavy rain may also be an issue
these easterlies are often maximal in late afternoon due to additive effects of sea breezes which increase gustiness
when forecast easterly wind gusts at the Lighthouse are over 50-60kph, it is likely that camping will be very unpleasant with lots of raised dust and potential damage to tents and gazebos
in La Nina periods in Feb-March can cause either:
blocking Highs in the Tasman can result in low pressure systems in NSW from tracking eastward and these extremely moist and vigorous systems can then cause flooding in east coast of NSW then track down to eastern Bass Strait where they can then send very moist strong easterlies which may create major rain events (see below) with a easterly wind pushed leeward standing rain cloud over Tidal River such as the March 2011 and March 2021 rain events.
Low pressure systems off the NSW coast pushing Highs south-eastwards over Tasmania and creating persistent strong dry easterlies as in:
beware the strong cold fronts and thunderstorms
falling trees and flash flooding can occur, and in summer, lightning can create added danger of bushfires.
a strong southerly can drop the temperatures to much below usual levels and can overcome the general stabilising effect of Bass Strait water temperature
weather conditions can change quickly and showers and storms can impact your stay
the cool sea breezes on a sunny day make it very pleasant but remember in Spring and Summer the UV index is likely to be high so you need sun protection and plenty of water to drink
most of the rain falls over winter when it rains 19 days per month with a monthly average rainfall of 120mm
it still rains in Summer but only on 10 days per month with a monthly average rainfall of 50mm
Bushfires may impact the park
there is only one road in or out!
13% of the park was burnt in 2005
25,000 hectares burnt in 2009 after a lightning strike near Sealer's Cove and burned to within 1km of Tidal River camp ground
severe rain events leading to flooding may impact the park
Tidal River camp ground was flooded in March 2011 (up to one metre of water inside the park’s information centre) and the bridge over Darby River was cut stranding 300 campers and requiring helicopter transport out (including 53 picked up from Sealers Cove) after a freakish storm (thought yo be a 1 in 3000 year event)
1) delivered 370mm rain in 24hrs (Victoria's record is 375mm in 24hrs in the Otways in 1983, next highest is 318mm at Mt Wellington in 2007 due to an east coast low). A large land slip also resulted visible from the Lilli Pilli Circut Walk in addition to land slips on the Telegraph Road which was also lost in two sections. Loo-Ern track was destroyed and the cabins had to be re-built. Debris from flooding was on top of the railing of the pedestrian bridge at Tidal River. Tidal River and areas south of Cotters Beach were closed to public for months.
2)3)
this event was associated with one of the strongest La Nina events and was caused by a low pressure system which was cut off in easterly flow in southern NSW on 21st March 2011 with an associated trough which extended southwards to Bass Strait and northwards to north-east NSW. The low had moved across south-eastern Sth Aust where ten locations had record March daily rainfall totals on 21st March. BY 22nd March, a low pressure centre had developed in the trough in western Bass Strait as the initial low moved to southern NSW bringing very heavy rainfalls to the southern NSW coast including Merimbula where the nearby Mt Darragh recorded almost 400mm in 24hrs on 22nd March. The two low centres were linked by the trough. During this period a mesoscale low developed 70km south of Lakes Entrance creating a vigorous and deep moist gale force easterly flow to be incident on Wilsons Prom's steep north-south terrain (Mt Latrobe elevation 754m is 5.8km to the ENE of Tidal River and causes steep topographic uplift of an easterly with the resulting standing wave of cloud formation able to be shifted leeward in very strong easterly winds and result in maximum rainfall on the leeward side and thus impacting Tidal River instead of the usual impacts on the east side - Sealers Cove only had 70mm rain. The east-west orientation of the valleys has potential to create convergence and greater uplift.) until this low tracked south of the Prom on the morning of 23rd March. Tidal River was hit by three separate periods of 3 hour rains within the 24hr period, each totaling over 100mm occurred. This rain event also impacted north-east coast of Tasmania with Gray recording 327mm on 24th March.
4)
Tues 23rd March 2021, a similar rain event caused by a blocking High pressure system in the Tasmania creating a Low trough in eastern coast of NSW causing extreme flooding and then developed into a blocked low which travelled south to a few kms east of the Prom resulting in over 100mm rain in 2hrs at lighthouse with winds next evening gusting over 130kph. In 2 days, Tidal River recorded some 230mm rain and lost perhaps 6-10“ of beach sand although the high tide at time of highest wind gusts seem to have protected most of the beach. The Park was closed for 2 days.