«All year round, I’m waiting for Summer» is the starting line of the famous ballade “Azzuro” by Adriano Celentano; many Swiss must have been thinking about Italy’s blue skies when planning their summer vacations. The payment data from SIX shows that a disproportionately large number of foreign transactions has been made with Swiss debit cards in Italy: For example, at SFr. 37.6M per week, volumes were 64% higher at the peak (week 30: 07/26-01/08) than in 2020 (week 32) and still 53% higher than in pre-pandemic 2019 (week 31). 
Looking at spending by merchant category, we see that those categories related to tourism (lodging, restaurants, gas stations, transportation services) nearly doubled compared to last year (2021: 19.7M CHF in week 30; 2020: 10.4M CHF in week 32). Expenditures that could also be related to cross-border shopping (food, other retailers) have by comparison increased more slowly (2021: 15.2M CHF in week 30; 2020: 10.9M CHF in week 32).
Figure 1. Debit card spending by Swiss cardholders in Italy, per week in million CHF – Merchants related to tourism.
Added to this are cash withdrawals in Italy amounting to around SFr. 14M, which were only marginally lower than in 2019.  Therefore, the sharp increase cannot be attributed to a corresponding reduction in cash usage either.
A comparison with France, Austria and Germany is also interesting: https://monitoringconsumption.com/debitcard_cross_border/
In France, we see a 10% increase in spending levels compared to the peak weeks of 2020 at 32M SFr. and 18% compared to 2019. However, unlike Italy, cash withdrawals in France have declined more (9.8M SFr. in 2021 vs. 11.4M SFr. in 2020 and 9.5M SFr. in 2019). Debit card transactions in Austria remain below 2020 and 2019 levels (7.3M SFr. in 2021 vs. 8.7M SFr. in 2020 and 8.4.M SFr. in 2019) amid sharp declines in cash withdrawals (1.7M SFr. in 2021 vs. 2.3M SFr. in 2020 and 2.9.M SFr. in 2019). In Germany, spending lies between 2019 and 2020 levels at 24.5M per week; however, a decomposition by merchant category suggests that the dominant share of spending is likely due to cross-border shopping rather than tourism.
But why does ‘azzurro’ score so well with Swiss holidaymakers? We can only speculate on the reasons: Geographic proximity and a comparatively mild overland entry regime or relatively low virus incidences relative to France or Spain may have played a role. 
Figure 2. Debit card issues by Swiss cardholders abroad, per week in million CHF – All merchant categories.
 The shifts mostly result from moving vacations.
 Only cash withdrawals abroad can be registered. Euro cash withdrawals in Switzerland before traveling abroad cannot be shown separately in the data.
 Translated by Monitoring Consumption Switzerland with the help of www.DeepL.com/Translator (free version).