Table 2.

Overview of the adverse weather indices used in this study.

Indicator name		Effect on wheat	Event trigger / Indicator description
1	Frost with no snow	Leaf chlorosis; burning of leaf tips, severe crop damage (Trnka et al., 2010b)	Tmin a ≤ −20 °C for at least 1 day with no or very limited snow coverb (< 1 cm snow)
2	Late frost	After the loss of winter-hardiness leads to leaf chlorosis, floret sterility, damage to lower stem (Gusta and Fowler, 1976; Petr, 1991)	Tmin a is ≤ −2 °C, after mean air temperature is continuously 10 °C (for at least 5 days) and does not drop below 10 °C for more than 2 days in a row
3	Extremely wet early season	Occurrence of diseases, nitrogen leaching, waterlogging and root anoxia (Bartholomeus et al., 2008; Malik et al., 2002)	Soil moisture is at or above field capacity for >60 days from sowing to anthesis. Days with a mean temperature <3 °C are not counted
4	Lodging	Severe reduction of yield and grain quality, through increased harvest losses and exposure to diseases (Berry et al., 2003; Russell and Wilson, 1994)	At least 2 days (from anthesis to 5 days before maturity) with daily precipitation >40 mm, or >20 mm and soil moisture on the previous day at or above field capacity.
5	Grain filling extreme heat	Speeds up development and decreases yield until the growth stops (Nasehzadeh and Ellis, 2017; Savill et al., 2018)	Tmaxc > 35 °C for at least 3 days during the period from 5 days after anthesis to maturity
6	Adverse sowing conditions	Restricts the ability to use the appropriate sowing window (Trnka et al., 2014, 2011)	Fewer than 3 days during the sowing windowd with the soil moisture in the top layer <90% but >5% and rain on the day is <5 mm and ≤10 mm on the preceding day
7	Adverse harvest conditions	Restricts the ability to harvest at the most appropriate time (Trnka et al., 2014, 2011)	Fewer than 3 days during the harvest windowe with soil moisture in the top layer <85% and rain on the given day is <0.5 mm and ≤5 mm on the preceding day
8	Heat stress index (HSI)	Heat stress during the reproductive period causes partial or complete sterility of the florets (Alghabari et al., 2014; Porter and Gawith, 1999)	$\mathit{HSI}=(1-\frac{Y_{\mathit{wh}}}{Y_w})$ where Ywh is water and heat limited yield of heat sensitive, drought tolerant, Mercia.
9	Drought stress index (DSI)	Drought stress during the reproductive period causes premature abortion of florets and sterility (Dong et al., 2017; Ma et al., 2017)	$\mathit{DSI}=(1-\frac{Y_{\mathit{wd}}}{Y_w})$ where Ywd is water-limited yield of drought sensitive, heat tolerant, Mercia.
10	Water stress index (WSI)	Water stress during the entire growing season causes severe reduction of growth or crop die back (Jamieson et al., 1998)	$\mathit{WSI}=(1-\frac{Y_w}{Y})$ where Y is potential yield (not limited by water) of heat and drought tolerant Mercia, Yw is water-limited yield (rain fed only) of heat and drought tolerant Mercia.

^aThe Tmin minimum daily temperature was measured 2 m above ground; thus, the actual crop temperature might be even lower.

^bThe snow cover was estimated using a model validated by Trnka et al. (2010b).

^cThe Tmax maximum daily temperature was measured 2 m above ground.

^dThe sowing window is sowing date ±15 days.

^eThe harvest window is maturity date + 5 days, to maturity + 25 days.