(* Data Source: https://w2.weather.gov/climate/xmacis.php?wfo=box  *)
(* Mathematica, Oliver Knill, Math 1a, Apr 25, Spring 2020         *)

A={
{1900,30.1,29.3,34.0,48.5,55.2,68.6,73.9,71.1,64.9,56.6,44.7,33.5,50.9},
{1901,27.6,24.3,36.2,43.5,54.3,68.2,73.5,70.7,65.4,54.4,37.3,32.5,49.0},
{1902,26.9,28.9,43.3,48.4,57.8,64.3,67.9,67.6,62.6,53.6,46.2,28.6,49.7},
{1903,28.6,31.4,44.4,47.9,58.5,59.8,71.4,65.0,64.4,53.9,40.0,29.0,49.5},
{1904,21.5,22.6,34.5,44.7,60.9,64.0,71.4,68.7,62.5,50.5,38.2,25.8,47.1},
{1905,25.1,23.4,37.1,46.8,57.6,65.2,73.2,68.6,62.0,53.6,41.6,35.1,49.1},
{1906,36.4,29.7,32.3,47.2,58.0,66.4,70.1,72.0,65.0,52.5,41.7,29.1,50.0},
{1907,27.0,21.7,37.9,43.4,52.5,65.1,72.4,69.7,64.4,49.8,43.3,37.2,48.7},
{1908,32.0,26.7,38.6,46.8,59.0,69.9,74.1,69.4,65.8,55.4,43.6,33.3,51.2},
{1909,30.3,32.6,36.8,47.7,55.8,69.4,71.5,69.4,62.6,52.8,46.4,30.7,50.5},
{1910,32.0,29.5,42.0,51.6,57.6,65.2,74.9,68.8,62.8,56.0,41.2,27.5,50.8},
{1911,31.8,27.0,35.5,46.1,62.5,65.5,77.1,69.0,62.5,52.6,41.9,39.4,50.9},
{1912,21.4,27.7,36.0,47.4,58.6,68.0,73.2,68.9,63.7,57.5,45.7,38.5,50.6},
{1913,39.3,27.7,42.4,48.0,55.1,67.5,73.8,70.7,62.0,56.5,46.5,37.8,52.3},
{1914,28.7,24.3,36.7,45.3,60.0,67.3,68.6,70.4,64.6,57.0,42.7,30.4,49.7},
{1915,33.1,33.2,35.8,50.7,56.6,63.9,70.1,69.1,66.8,55.7,45.4,34.2,51.2},
{1916,33.1,25.5,30.6,45.6,58.6,62.7,72.6,71.7,65.0,55.5,42.6,32.6,49.7},
{1917,30.2,25.8,37.3,44.0,50.7,65.8,73.3,72.9,60.3,51.9,39.5,23.7,48.0},
{1918,21.0,27.0,36.7,47.8,63.3,63.9,71.1,70.4,61.1,56.1,45.0,34.7,49.8},
{1919,33.3,32.6,40.8,46.8,59.1,67.3,74.0,68.8,63.9,55.1,42.7,28.7,51.1},
{1920,21.0,27.6,39.3,45.1,54.6,65.8,72.4,72.0,65.3,59.8,41.7,35.6,50.0},
{1921,32.1,32.5,46.2,51.7,58.0,68.2,73.2,69.6,68.5,55.2,41.5,31.3,52.3},
{1922,27.2,32.0,39.8,48.7,61.4,68.7,72.0,70.4,65.2,55.1,43.8,30.9,51.3},
{1923,26.9,23.6,33.8,48.1,57.6,69.3,69.9,69.3,64.4,55.6,44.7,40.4,50.3},
{1924,31.9,26.8,37.5,47.3,56.2,66.7,73.8,71.9,62.2,54.6,45.4,31.1,50.4},
{1925,27.1,38.1,43.1,49.8,57.4,70.9,72.3,71.1,64.1,49.5,43.6,33.6,51.7},
{1926,31.0,27.9,34.3,44.8,56.0,64.3,70.5,70.4,62.4,53.4,44.2,28.6,49.0},
{1927,30.7,32.6,41.6,48.3,55.2,65.1,72.2,67.5,65.0,57.9,49.6,35.9,51.8},
{1928,32.9,29.6,37.0,46.8,55.3,65.0,73.2,73.6,62.4,56.6,44.8,38.8,51.3},
{1929,29.0,31.7,41.4,46.6,61.0,68.3,72.6,69.2,65.3,53.2,44.7,32.6,51.3},
{1930,31.8,34.1,38.1,47.5,59.7,72.4,72.8,70.5,69.4,53.0,45.1,33.2,52.3},
{1931,30.5,30.3,39.3,50.2,60.3,67.2,74.0,72.1,66.9,58.5,49.5,36.6,53.0},
{1932,38.8,30.7,35.6,47.5,60.3,66.5,72.8,74.0,65.1,57.1,42.8,38.1,52.4},
{1933,37.9,33.7,35.7,46.5,61.6,69.4,70.7,71.7,65.8,52.5,38.3,26.9,50.9},
{1934,29.6,17.5,35.0,48.0,60.6,66.9,73.1,67.3,64.5,49.5,45.6,28.5,48.8},
{1935,23.2,27.9,38.4,45.2,55.5,65.5,72.6,70.7,61.5,53.8,45.4,27.1,48.9},
{1936,28.2,22.8,41.8,45.3,60.6,66.6,71.1,69.7,62.6,54.5,39.5,34.9,49.8},
{1937,37.4,33.2,34.1,45.3,59.1,66.4,73.2,74.5,62.9,52.6,44.0,31.2,51.2},
{1938,28.0,30.6,39.1,48.7,55.8,67.3,71.8,73.6,62.2,56.0,46.4,34.0,51.1},
{1939,27.9,32.4,32.9,43.8,56.4,65.7,72.3,73.8,64.5,54.1,40.8,33.4,49.8},
{1940,23.0,29.6,33.1,43.6,56.3,65.1,71.5,68.5,63.3,50.6,42.9,34.3,48.5},
{1941,25.3,29.4,33.4,51.6,59.9,68.2,71.4,70.6,66.0,55.9,48.0,35.2,51.2},
{1942,28.5,27.2,40.8,49.7,60.7,67.4,71.1,70.7,64.5,55.8,43.5,28.6,50.7},
{1943,25.5,30.6,36.0,43.4,57.6,71.1,74.1,71.0,62.9,53.9,43.3,29.5,49.9},
{1944,30.9,29.6,34.1,44.7,63.2,67.0,73.8,74.7,65.0,53.7,43.2,30.8,50.9},
{1945,23.7,30.5,46.3,52.5,55.1,66.6,71.9,70.7,67.1,53.1,45.5,28.5,51.0},
{1946,28.3,27.6,47.2,46.1,58.0,67.5,70.9,67.8,65.9,58.4,47.9,34.8,51.7},
{1947,32.6,29.6,37.7,47.1,56.9,65.4,74.3,73.1,64.7,61.5,41.2,30.4,51.2},
{1948,23.3,26.9,38.0,48.0,55.0,63.6,74.5,73.7,65.7,54.3,49.6,36.3,50.7},
{1949,34.7,34.4,39.2,50.9,60.3,71.6,76.3,74.4,63.2,58.4,43.5,36.8,53.6},
{1950,36.2,28.0,33.7,46.7,55.8,69.1,73.5,70.8,61.5,56.3,47.8,35.5,51.2},
{1951,34.0,34.7,39.0,51.0,59.1,66.0,74.0,70.6,65.5,54.8,42.6,35.0,52.2},
{1952,32.6,32.5,37.2,50.5,57.2,70.6,77.5,72.2,66.3,53.0,44.9,35.6,52.5},
{1953,34.7,35.0,39.0,48.9,58.4,70.5,73.2,72.0,66.3,56.2,48.6,40.1,53.6},
{1954,25.9,36.4,38.8,50.1,56.3,66.6,72.1,70.1,63.2,58.6,44.4,34.4,51.4},
{1955,28.5,32.0,37.6,49.2,62.7,66.8,77.2,74.5,64.5,55.1,41.9,26.6,51.4},
{1956,30.6,32.5,33.5,45.6,55.4,68.9,71.7,71.8,61.1,54.3,46.1,36.0,50.6},
{1957,23.4,34.6,39.0,49.4,59.8,71.3,74.1,69.3,67.3,54.5,47.1,40.0,52.5},
{1958,31.0,25.5,39.0,48.7,56.6,63.9,72.4,72.4,64.6,52.6,46.5,26.4,50.0},
{1959,28.7,26.7,37.0,48.9,62.6,64.6,74.7,74.1,68.1,55.0,44.4,36.3,51.8},
{1960,30.9,35.3,32.7,48.3,59.7,69.6,73.1,72.2,63.7,53.9,48.0,29.5,51.4},
{1961,25.0,31.6,36.8,45.2,56.3,68.9,72.1,72.5,68.9,57.3,44.6,32.8,51.0},
{1962,28.7,26.7,38.5,49.3,57.2,68.4,70.3,69.9,62.9,54.1,41.7,30.0,49.8},
{1963,29.5,25.9,39.0,48.9,59.4,69.4,74.7,70.4,60.8,60.0,48.3,25.8,51.0},
{1964,31.7,29.1,38.7,46.1,60.3,67.0,71.5,66.4,62.0,52.5,44.1,32.4,50.2},
{1965,25.4,27.9,35.8,44.2,59.5,67.4,71.0,70.5,62.5,52.8,42.1,36.1,49.6},
{1966,28.8,31.3,39.7,45.9,57.2,69.4,74.9,71.2,63.5,54.4,46.8,34.2,51.4},
{1967,35.1,26.4,33.1,44.9,51.6,67.2,72.9,70.8,62.7,53.7,40.1,34.9,49.5},
{1968,25.5,26.0,39.1,49.6,56.1,64.8,75.2,70.7,64.9,57.9,43.8,30.9,50.4},
{1969,29.3,29.4,35.4,50.6,58.5,69.3,71.0,74.3,63.7,54.3,44.9,33.4,51.2},
{1970,23.0,32.3,37.4,49.0,59.6,67.0,74.2,73.6,65.6,54.9,44.8,28.9,50.9},
{1971,23.7,30.4,36.7,45.1,55.7,69.1,73.4,73.4,67.9,59.8,43.1,36.3,51.2},
{1972,33.0,29.6,36.3,44.9,57.6,65.4,73.7,71.5,65.7,51.8,42.3,33.0,50.4},
{1973,31.4,30.1,43.3,49.9,57.0,70.0,74.2,74.8,64.4,55.6,45.8,39.5,53.0},
{1974,31.7,29.1,38.7,50.8,54.7,64.8,72.4,72.0,63.7,50.0,45.3,37.7,50.9},
{1975,34.9,32.0,36.8,45.1,61.4,67.5,75.9,72.9,63.9,57.3,51.8,34.4,52.8},
{1976,26.1,37.3,41.1,55.1,60.2,73.4,72.9,71.9,64.9,52.3,41.9,29.0,52.2},
{1977,23.2,30.7,44.7,51.3,62.6,67.4,74.9,73.4,64.4,55.3,48.1,34.2,52.5},
{1978,28.4,27.0,36.2,48.8,59.3,68.2,72.0,71.6,61.4,52.5,43.5,35.3,50.3},
{1979,32.5,23.1,42.5,48.7,61.1,68.2,74.5,71.7,64.9,52.6,48.6,36.6,52.1},
{1980,29.4,27.8,36.8,48.7,59.4,66.3,75.8,74.2,66.9,52.4,41.2,28.6,50.6},
{1981,21.4,36.4,39.1,51.7,60.4,70.7,74.6,72.0,63.6,51.2,43.8,33.2,51.5},
{1982,22.9,30.8,38.6,48.2,57.8,63.3,74.8,70.3,64.0,54.2,47.6,39.5,51.0},
{1983,31.2,32.8,40.6,49.1,58.1,70.7,78.0,73.6,70.6,55.1,46.1,32.1,53.2},
{1984,26.6,37.5,31.8,46.1,58.0,70.5,74.7,74.6,62.1,53.2,44.5,39.5,51.6},
{1985,24.3,32.8,40.3,49.2,59.2,64.8,73.5,70.3,65.4,55.4,45.4,31.3,51.0},
{1986,31.4,28.8,40.7,48.4,58.4,66.0,71.0,70.5,63.2,54.0,42.3,35.5,50.9},
{1987,28.9,29.1,38.5,45.1,57.1,65.1,71.6,70.3,65.4,54.3,43.8,36.1,50.4},
{1988,27.8,32.1,39.2,46.8,57.6,68.5,73.7,75.5,64.6,50.8,46.7,32.8,51.3},
{1989,34.5,30.5,37.2,45.9,59.3,67.8,72.7,71.6,64.7,55.2,42.7,21.7,50.3},
{1990,36.4,34.1,40.1,47.6,54.9,66.6,73.1,73.3,64.6,58.3,48.5,40.7,53.2},
{1991,29.4,36.0,41.5,51.3,63.2,70.0,74.6,73.7,63.7,56.4,45.2,35.9,53.4},
{1992,31.0,32.4,35.4,46.3,55.5,67.7,69.4,70.3,63.9,52.4,42.9,34.8,50.2},
{1993,32.4,27.1,36.4,48.3,60.3,69.4,74.7,73.5,64.8,52.3,45.6,34.2,51.6},
{1994,22.2,26.9,38.1,51.4,58.4,71.9,77.5,72.4,64.2,55.5,48.9,38.5,52.2},
{1995,34.6,28.4,38.8,46.1,57.2,68.6,75.9,72.8,63.1,58.3,41.9,31.7,51.5},
{1996,30.1,30.9,36.5,47.9,57.4,68.1,71.8,70.9,64.1,53.2,40.3,39.2,50.9},
{1997,29.2,36.0,36.7,46.3,56.1,68.2,73.6,71.1,64.2,52.8,41.6,35.2,50.9},
{1998,33.9,35.2,41.5,49.4,60.3,64.6,74.3,72.5,66.3,54.4,44.6,39.1,53.0},
{1999,29.5,33.6,39.3,49.2,58.2,71.0,75.7,71.3,67.1,53.0,48.0,37.3,52.8},
{2000,27.5,34.2,43.3,47.3,57.2,67.3,70.0,70.3,63.5,53.9,43.8,29.2,50.6},
{2001,30.0,31.7,35.3,48.7,59.5,71.1,69.9,73.9,65.3,56.2,48.3,40.5,52.5},
{2002,36.7,36.3,40.2,49.7,57.7,66.5,75.2,75.2,68.4,52.4,42.9,33.1,52.9},
{2003,24.1,26.3,37.6,44.5,55.1,65.4,74.3,74.2,65.7,53.0,45.9,36.0,50.2},
{2004,20.7,33.0,39.4,49.5,58.8,66.5,71.0,72.0,65.2,53.8,44.3,35.0,50.8},
{2005,26.7,31.1,35.2,49.7,52.2,68.3,73.3,74.4,67.9,54.7,45.9,32.5,51.0},
{2006,36.5,31.0,38.7,49.8,57.0,68.1,75.9,71.4,64.6,54.3,49.1,41.0,53.1},
{2007,32.7,26.1,37.4,45.2,61.4,68.5,72.9,72.7,67.6,59.2,43.0,32.4,51.6},
{2008,33.4,32.5,38.2,49.3,57.7,70.3,75.0,70.0,65.3,53.3,43.4,35.7,52.0},
{2009,24.8,32.9,37.5,50.5,59.5,63.3,70.5,73.6,63.2,51.9,48.8,33.2,50.8},
{2010,29.6,33.2,43.9,53.0,62.8,70.3,77.2,73.4,68.7,55.6,44.8,32.7,53.8},
{2011,27.6,30.5,38.9,50.1,59.2,67.1,77.3,73.9,67.3,57.5,50.4,40.0,53.3},
{2012,34.1,37.3,46.7,53.1,60.3,66.8,75.3,74.6,64.7,56.5,42.1,38.4,54.2},
{2013,31.5,31.1,37.7,48.9,58.8,69.6,77.1,72.1,64.7,56.6,42.7,33.3,52.0},
{2014,27.4,28.9,33.5,48.1,58.7,68.3,74.1,70.8,66.2,56.4,42.5,38.2,51.1},
{2015,26.1,19.0,33.2,48.0,62.3,64.7,73.9,74.6,69.2,54.0,48.6,45.3,51.6},
{2016,32.5,34.7,42.5,47.1,58.6,68.4,76.1,76.4,67.5,55.3,46.2,35.2,53.4},
{2017,35.1,36.6,34.0,51.7,56.3,69.5,72.5,72.0,67.1,61.4,43.7,30.7,52.6},
{2018,28.6,38.1,37.2,45.3,62.1,67.7,76.1,77.4,69.0,54.4,42.9,37.3,53.0},
{2019,30.7,33.5,39.1,51.7,57.8,68.2,78.7,74.1,68.0,57.4,42.8,37.2,53.3}};

YearData[n_]:=Sum[A[[n,1+k]],{k,12}]/12; T=Length[A];
B = Flatten[Table[YearData[n],{n,T}]];S1=ListPlot[B]; 
f=Fit[B,{1,x},x];S2=Plot[f,{x,1,T}]; 
Export["bostontemperatures19002020.png",Show[{S1,S2}],"PNG"]