The COVID-19 pandemic had negative effects on many people's well-being and quality of life. In the present work, we focused on Norwegian mothers with elementary school children, and investigated whether their well-being, stress, and worries (and the relationships between them) changed across the early months of the pandemic. We collected data at two time points in 2020. In June 2020, 231 mothers (mean age = 40.09, SD = 6.22) responded to an online questionnaire in which they were asked to indicate their well-being, stress, and worries before the pandemic, during the lockdown (i.e., March 2020), and currently (i.e., June 2020). Of these 231 mothers, 97 (mean age = 40.58, SD = 5.66) answered the same questionnaire again in November 2020. Mothers' well-being was lower in November 2020 than before the pandemic (retrospectively reported). The age of the youngest child showed the strongest and most consistent relationship with mothers' well-being across all time points. In addition, we found that the stress mothers felt during the national lockdown in March 2020 was strongly associated with their well-being both during the lockdown and in June 2020. Finally, in November 2020, mothers' financial pandemic-related worries were negatively related to their well-being. Implications and suggestions for future research and for how societies can cope with future health-related crises are discussed.