Roxbury Airport
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Roxbury Airport clear sky chart from 2005-11-06 to 2024-01-15.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
27%
23037
18%
74650
8%
22992
39%
22992
19%
48298

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
14%
760
22%
2649
6%
757
35%
757
18%
1596
January11th to 20thNight
17%
739
18%
2583
5%
739
34%
739
14%
1715
January21st to endNight
15%
792
22%
2704
5%
792
36%
792
17%
1647
February1st to 10thNight
14%
720
16%
2303
3%
720
29%
720
14%
1554
February11th to 20thNight
11%
703
20%
2100
3%
700
30%
700
15%
1391
February21st to endNight
15%
592
23%
1776
7%
592
34%
592
15%
1174
March1st to 10thNight
16%
720
20%
2160
6%
720
34%
720
19%
1388
March11th to 20thNight
17%
720
19%
2100
5%
720
32%
720
17%
1399
March21st to endNight
17%
792
22%
1980
5%
792
30%
792
19%
1366
April1st to 10thNight
19%
720
18%
1800
3%
720
28%
720
19%
1277
April11th to 20thNight
21%
711
16%
1775
3%
711
28%
711
22%
1237
April21st to endNight
19%
639
18%
1719
3%
639
29%
639
20%
1199
May1st to 10thNight
21%
540
14%
1620
5%
540
29%
540
15%
1154
May11th to 20thNight
21%
414
18%
1476
10%
414
33%
414
15%
969
May21st to endNight
37%
389
14%
1551
12%
388
43%
388
18%
969
June1st to 10thNight
34%
360
16%
1440
11%
360
46%
360
17%
921
June11th to 20thNight
37%
360
13%
1440
12%
360
46%
360
19%
905
June21st to endNight
46%
360
15%
1440
13%
360
57%
360
22%
847
July1st to 10thNight
52%
350
13%
1400
16%
350
56%
350
21%
854
July11th to 20thNight
50%
348
13%
1392
15%
348
54%
348
21%
850
July21st to endNight
48%
394
18%
1486
19%
372
56%
372
23%
881
August1st to 10thNight
49%
410
16%
1474
12%
408
55%
408
25%
887
August11th to 20thNight
49%
710
13%
1774
7%
710
51%
710
26%
1265
August21st to endNight
50%
792
18%
1980
8%
792
53%
792
31%
1327
September1st to 10thNight
39%
720
21%
1800
9%
720
45%
720
29%
1216
September11th to 20thNight
46%
720
25%
1908
15%
720
52%
720
34%
1162
September21st to endNight
39%
720
24%
1980
14%
720
48%
720
26%
1307
October1st to 10thNight
32%
720
17%
2030
10%
720
39%
720
23%
1378
October11th to 20thNight
31%
720
22%
2160
11%
720
45%
720
25%
1362
October21st to endNight
23%
792
17%
2571
8%
792
35%
792
18%
1707
November1st to 10thNight
30%
740
23%
2407
11%
740
47%
740
23%
1450
November11th to 20thNight
24%
760
24%
2470
10%
760
41%
760
21%
1527
November21st to endNight
24%
760
22%
2526
8%
760
40%
760
20%
1547
December1st to 10thNight
20%
760
19%
2660
6%
760
35%
760
15%
1734
December11th to 20thNight
19%
760
17%
3194
4%
759
34%
759
12%
2002
December21st to endNight
15%
830
13%
4822
5%
817
34%
817
9%
3134

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
17%6%25%5%345%5%7%40%
74790
Night
18%7%35%5%3445%7%41%
74977
TransparencyDay
43%6%12%22%15%2
74495
Night
43%6%12%22%15%2
74806
SeeingDay
24%17%30%19%8%2
13858
Night
22%15%31%24%7%1
23043

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
14%8%344345%6%6%43%
1517
11th to 20thDay
18%8%45%5%45%6%6%8%34%
1472
21st to endDay
14%7%36%5%245%6%6%42%
1647
February1st to 10thDay
19%7%37%5%45%5%5%7%35%
1656
11th to 20thDay
15%6%35%5%4445%7%41%
1748
21st to endDay
20%9%26%5%34446%36%
1480
March1st to 10thDay
15%8%26%5%35%447%41%
1797
11th to 20thDay
17%5%26%5%36%5%5%7%37%
1855
21st to endDay
21%7%35%5%34335%40%
2376
April1st to 10thDay
19%7%35%5%35%45%6%38%
2160
11th to 20thDay
19%5%3443445%7%41%
2134
21st to endDay
22%5%25%5%34445%40%
2240
May1st to 10thDay
24%7%35%5%3445%6%33%
2340
11th to 20thDay
20%5%245%3446%7%40%
2432
21st to endDay
17%5%245%345%5%7%43%
2725
June1st to 10thDay
19%6%246%35%6%6%9%35%
2520
11th to 20thDay
17%7%35%5%35%5%6%8%35%
2520
21st to endDay
13%6%26%6%446%6%9%38%
2520
July1st to 10thDay
13%6%25%6%35%5%6%7%40%
2520
11th to 20thDay
12%5%35%5%35%6%6%10%40%
2520
21st to endDay
13%6%35%6%35%6%7%9%38%
2744
August1st to 10thDay
12%6%35%6%35%6%8%9%37%
2432
11th to 20thDay
13%6%25%6%35%6%7%9%38%
2126
21st to endDay
14%5%35%5%35%46%9%42%
2376
September1st to 10thDay
14%5%35%5%45%5%5%6%42%
2160
11th to 20thDay
13%6%2443445%7%50%
2052
21st to endDay
18%6%25%4345%5%6%43%
1980
October1st to 10thDay
23%7%34423445%40%
1926
11th to 20thDay
15%6%25%5%3445%7%45%
1800
21st to endDay
23%6%245%35%5%5%439%
1783
November1st to 10thDay
14%6%24423347%49%
1671
11th to 20thDay
19%6%2332445%6%45%
1710
21st to endDay
18%6%36%42436%7%43%
1653
December1st to 10thDay
20%8%25%6%34447%37%
1520
11th to 20thDay
23%6%2432435%6%43%
1906
21st to endDay
20%11%35%6%4445%7%32%
2772
January1st to 10thNight
16%7%25%42446%6%44%
2649
11th to 20thNight
21%7%25%5%3445%6%38%
2583
21st to endNight
13%9%3443445%7%44%
2704
February1st to 10thNight
18%9%46%434445%39%
2303
11th to 20thNight
16%8%45%5%3445%7%40%
2098
21st to endNight
20%7%35%434345%41%
1776
March1st to 10thNight
17%7%25%425%45%7%43%
2150
11th to 20thNight
16%8%25%5%35%5%47%40%
2099
21st to endNight
18%6%35%434447%41%
1980
April1st to 10thNight
19%7%35%5%25%5%5%7%37%
1800
11th to 20thNight
19%5%25%5%345%5%6%40%
1775
21st to endNight
21%6%36%5%23346%41%
1719
May1st to 10thNight
23%8%36%5%3445%7%32%
1620
11th to 20thNight
19%8%25%5%3445%7%39%
1475
21st to endNight
17%7%3443446%7%41%
1550
June1st to 10thNight
19%6%35%5%345%47%40%
1440
11th to 20thNight
17%6%25%5%25%5%5%9%39%
1440
21st to endNight
14%5%244345%5%10%43%
1440
July1st to 10thNight
15%425%435%5%7%8%42%
1440
11th to 20thNight
14%5%26%5%336%7%10%39%
1440
21st to endNight
11%5%26%5%35%5%7%8%42%
1574
August1st to 10thNight
9%6%25%6%35%6%7%7%44%
1484
11th to 20thNight
13%5%35%7%46%5%6%8%38%
1774
21st to endNight
16%5%2443445%8%45%
1980
September1st to 10thNight
16%7%25%5%34446%45%
1800
11th to 20thNight
14%5%24323336%54%
1908
21st to endNight
17%6%2443444446%
1980
October1st to 10thNight
21%7%35%42235%6%42%
2030
11th to 20thNight
16%5%25%5%33447%46%
2160
21st to endNight
23%6%2442445%5%40%
2571
November1st to 10thNight
13%6%25%42445%6%48%
2407
11th to 20thNight
19%6%34424346%45%
2470
21st to endNight
16%6%245%24446%46%
2526
December1st to 10thNight
21%6%35%42445%6%39%
2660
11th to 20thNight
20%7%244345%46%40%
3288
21st to endNight
23%10%45%42335%5%35%
4884

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
40%5%12%28%12%4
1518
11th to 20thDay
48%7%13%19%12%2
1472
21st to endDay
40%5%12%24%15%3
1647
February1st to 10thDay
48%6%13%19%13%2
1656
11th to 20thDay
42%5%11%22%16%3
1757
21st to endDay
50%410%21%13%3
1480
March1st to 10thDay
43%5%13%22%14%4
1800
11th to 20thDay
44%6%11%23%14%2
1855
21st to endDay
49%48%18%17%5%
2376
April1st to 10thDay
46%6%11%20%15%3
2160
11th to 20thDay
42%6%11%22%17%3
2134
21st to endDay
45%6%10%20%15%4
2240
May1st to 10thDay
51%5%9%19%14%2
2340
11th to 20thDay
43%7%11%20%17%3
2436
21st to endDay
41%8%16%20%13%2
2725
June1st to 10thDay
45%7%14%21%11%1
2520
11th to 20thDay
44%8%13%22%11%1
2520
21st to endDay
41%8%15%23%13%1
2520
July1st to 10thDay
42%8%12%21%16%1
2450
11th to 20thDay
38%8%15%24%13%1
2445
21st to endDay
41%8%14%18%16%2
2591
August1st to 10thDay
40%9%14%24%12%
2418
11th to 20thDay
39%8%17%22%12%1
2126
21st to endDay
39%6%12%23%18%2
2376
September1st to 10thDay
41%8%11%21%17%1
2160
11th to 20thDay
34%6%10%23%24%2
2052
21st to endDay
41%7%10%21%18%3
1980
October1st to 10thDay
46%6%9%22%15%3
1926
11th to 20thDay
38%6%13%27%15%2
1800
21st to endDay
47%411%21%14%3
1783
November1st to 10thDay
37%412%26%18%3
1671
11th to 20thDay
39%412%24%18%3
1710
21st to endDay
41%414%27%12%3
1653
December1st to 10thDay
48%5%14%18%14%1
1520
11th to 20thDay
42%5%15%20%15%2
1906
21st to endDay
53%6%10%22%9%1
2772
January1st to 10thNight
40%413%24%15%3
2649
11th to 20thNight
45%7%14%21%10%2
2583
21st to endNight
40%5%12%23%18%3
2704
February1st to 10thNight
48%5%13%21%12%2
2303
11th to 20thNight
45%5%11%19%16%4
2100
21st to endNight
45%49%23%14%4
1776
March1st to 10thNight
40%6%13%23%15%3
2160
11th to 20thNight
44%5%10%22%16%3
2100
21st to endNight
44%410%18%19%5%
1980
April1st to 10thNight
45%6%11%21%14%3
1800
11th to 20thNight
43%6%12%19%19%1
1775
21st to endNight
45%6%9%22%14%4
1719
May1st to 10thNight
52%6%11%17%13%2
1620
11th to 20thNight
46%6%9%19%17%2
1476
21st to endNight
43%7%16%21%12%1
1551
June1st to 10thNight
46%6%9%22%16%1
1440
11th to 20thNight
41%9%15%24%10%1
1440
21st to endNight
36%9%15%25%15%1
1440
July1st to 10thNight
38%9%15%21%14%2
1400
11th to 20thNight
39%9%16%27%9%1
1392
21st to endNight
37%8%16%22%14%3
1486
August1st to 10thNight
35%10%16%24%14%1
1474
11th to 20thNight
42%9%16%22%10%1
1774
21st to endNight
37%9%12%23%19%1
1980
September1st to 10thNight
41%6%10%25%17%1
1800
11th to 20thNight
33%6%11%23%25%2
1908
21st to endNight
40%6%8%22%21%2
1980
October1st to 10thNight
44%6%11%22%14%3
2030
11th to 20thNight
38%6%12%28%14%1
2160
21st to endNight
46%5%12%21%14%1
2571
November1st to 10thNight
37%6%12%22%20%4
2407
11th to 20thNight
41%410%23%17%4
2470
21st to endNight
40%5%14%29%12%1
2526
December1st to 10thNight
46%6%12%22%13%1
2660
11th to 20thNight
44%6%14%19%15%2
3288
21st to endNight
51%5%12%21%11%
4884

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
34%22%28%14%2
180
11th to 20thDay
32%30%26%11%1
168
21st to endDay
25%32%30%8%4
204
February1st to 10thDay
38%25%26%10%1
276
11th to 20thDay
31%26%32%10%1
416
21st to endDay
33%24%31%9%2
346
March1st to 10thDay
29%21%35%13%3
420
11th to 20thDay
28%27%31%11%21
420
21st to endDay
32%23%30%10%32
462
April1st to 10thDay
32%26%25%10%7%1
420
11th to 20thDay
30%20%30%13%5%1
412
21st to endDay
32%20%31%12%5%1
420
May1st to 10thDay
35%19%29%11%6%1
423
11th to 20thDay
24%19%36%16%41
447
21st to endDay
21%11%31%24%11%2
485
June1st to 10thDay
22%12%31%23%10%2
450
11th to 20thDay
19%15%34%21%10%2
450
21st to endDay
16%13%31%27%11%1
450
July1st to 10thDay
16%8%32%27%15%3
445
11th to 20thDay
12%9%32%28%16%2
444
21st to endDay
12%10%36%28%12%1
488
August1st to 10thDay
14%9%28%33%12%5%
446
11th to 20thDay
15%7%28%31%13%5%
439
21st to endDay
12%12%30%25%15%6%
495
September1st to 10thDay
19%12%27%21%16%6%
450
11th to 20thDay
16%12%29%25%10%8%
450
21st to endDay
20%15%30%21%10%5%
450
October1st to 10thDay
31%10%28%14%13%4
450
11th to 20thDay
16%24%29%23%7%2
450
21st to endDay
31%15%30%18%7%
396
November1st to 10thDay
21%16%27%24%9%2
365
11th to 20thDay
29%22%27%18%41
370
21st to endDay
25%21%30%18%5%
313
December1st to 10thDay
30%21%32%13%4
180
11th to 20thDay
39%23%25%11%1
180
21st to endDay
28%27%26%14%42
198
January1st to 10thNight
25%19%38%16%3
760
11th to 20thNight
28%21%30%19%2
739
21st to endNight
22%23%35%17%3
792
February1st to 10thNight
27%20%34%18%2
720
11th to 20thNight
26%22%37%14%1
703
21st to endNight
29%22%31%16%2
592
March1st to 10thNight
26%21%34%17%3
720
11th to 20thNight
23%24%33%16%31
720
21st to endNight
25%21%32%17%4
792
April1st to 10thNight
26%22%31%18%3
720
11th to 20thNight
23%20%33%20%4
711
21st to endNight
25%21%33%17%41
639
May1st to 10thNight
28%15%32%20%5%
540
11th to 20thNight
22%18%34%22%3
414
21st to endNight
20%8%29%33%8%2
389
June1st to 10thNight
21%7%32%29%11%1
360
11th to 20thNight
18%8%30%33%11%
360
21st to endNight
17%427%43%9%
360
July1st to 10thNight
15%5%23%37%20%
350
11th to 20thNight
12%5%26%41%14%2
348
21st to endNight
12%428%39%16%
394
August1st to 10thNight
10%429%41%15%1
410
11th to 20thNight
15%6%22%36%19%2
710
21st to endNight
16%6%21%38%18%2
792
September1st to 10thNight
17%6%30%33%12%2
720
11th to 20thNight
17%8%25%31%16%3
720
21st to endNight
22%8%26%27%15%2
720
October1st to 10thNight
24%11%28%25%12%1
720
11th to 20thNight
19%15%31%27%8%1
720
21st to endNight
28%14%33%19%7%
792
November1st to 10thNight
18%15%32%25%8%1
740
11th to 20thNight
23%17%33%19%7%1
760
21st to endNight
23%18%30%22%5%1
760
December1st to 10thNight
28%18%31%19%41
760
11th to 20thNight
25%22%29%21%3
760
21st to endNight
29%18%34%17%2
836
Page generated at 2024-01-12 07:31:51. Version ac07

Copyright 2024 Attilla Danko


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