“Sprinter” (spring + winter) is a portmanteau word that has been printed on many images.
       
“Sprummer” (spring + summer) is a related term.
 
         
Wiktionary: sprinter
Etymology
Blend of spring +‎ winter
Noun
sprinter (uncountable)
1. Transition period between winter and spring: late winter.
 
Urban Dictionary   
sprinter
A short season in Saskatchewan that happens during April. It consists of warm temperatures one week only to be followed by below zero temperatures and large amounts of blowing snow.
I can’t take anymore of this Sprinter. I wish summer would arrive already.
by Macbeth42 May 3, 2005
   
Urban Dictionary
sprinter
a season that falls between winter and spring in New England and Canada. Consists of snow in April. It ends around mid-April, usually.
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by Karen Stickney March 31, 2007
   
Google Groups: alt.fan.cecil-adams
A unique and logic-defying blend of summer and winter
Joseph Nebus
Aug 24, 2009, 11:11:37 AM
Now and then the world serves up a headline that can’t help but make me happy, and leave me feeling vaguely inspired. I’m going to be busy all day thinking of new concepts for seasons for Australia, no matter what they think they want.
http://news.bbc.co.uk/2/hi/asia-pacific/8215570.stm
 
Australians ‘need more seasons’
 
An Australian scientist says the continent needs five or six seasons to suit its climate.
 
Tim Entwisle, chief of Sydney’s Royal Botanic Gardens, says Australia should “unhook” itself from the “arbitrary” four seasons it inherited from Britain.
 
Mr Entwisle has proposed “sprummer” - the season between spring and summer - and “sprinter” - an early spring.
 
OCLC WorldCat record
Sprinter and sprummer : Australia’s changing seasons
Author: Timothy J Entwisle
Publisher: Collingwood, Vic. : CSIRO Publishing, 2014.
Edition/Format:   eBook : Document : National government publication : English
Summary:
Sprinter and Sprummer challenges the traditional four seasons, and encourages us to think about how we view changes in our natural world. Since 1788, Australia has carried the yoke of four European seasons that make no sense in most parts of the country. We may like them for historical or cultural reasons, or because they are the same throughout the world, but they tell us nothing of our natural environment. It’‘s time to reject those seasons and to adopt a system that brings us more in tune with our plants and animals - a system that helps us to notice and respond to climate change. Using examp.
 
CSIROscope
Five seasons in Australia? Meet sprinter and sprummer
BY MARY-LOU CONSIDINE 13 JUN, 2018
(...)
In his book Sprinter and Sprummer, botanist Tim Entwisle argues the case for a five-season calendar that more closely reflects antipodean cycles in weather, and plant and animal activity.