Using a currently most representative sample of 477 late-type galaxies within 11Mpc of the Milky Way with measured star formation rates (SFRs) from the far-ultraviolet (FUV) and H{alpha} emission line fluxes, we select galaxies with the extreme ratios: SFR(H{alpha})/SFR(FUV)>2 and SFR(H{alpha})/SFR(FUV)<1/20. Each subsample amounts to ~5 per cent of the total number and consists of dwarf galaxies with the stellar masses M/M_{sun}_=(5.5-9.5)dex. In spite of a huge difference in their SFR(H{alpha}) activity on a scale of ~10Myr, the temporarily 'excited' and temporarily 'quiescent' galaxies follow one and the same relation between SFR(FUV) and M on a scale of ~100Myr. Their average specific SFR log[SFR(FUV)/M*]=-10.1+/-0.1yr^-1^) coinsides with the Hubble parameter log(H_0_)=-10.14(yr^-1^). On a scale of t~10Myr, variations of SFR have a moderate flash amplitude of less than one order above the main sequence and a fading amplitude to two orders below the average level. In general, both temporarily excited and temporarily quiescent galaxies have almost similar gas fractions as normal main-sequence galaxies, being able to maintain the current rate of star formation on another Hubble time-scale. Ranging the galaxies according to the density contrast produced by the nearest massive neighbour exhibits only a low average excess of SFR caused by tidal interactions.

Cone search capability for table J/MNRAS/506/1346/tablea1 (Stellar masses and SFRS of late-type galaxies in the LV)