Quincy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Quincy clear sky chart from 2005-11-05 to 2018-01-20.

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
60%
15610
26%
48501
23%
15579
65%
15579
37%
26431

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 15thNight
50%
777
19%
2716
16%
776
57%
776
27%
1599
January16th to endNight
42%
788
23%
2571
18%
788
51%
788
25%
1596
February1st to 15thNight
48%
697
21%
2281
18%
697
55%
697
25%
1387
February16th to endNight
48%
632
23%
1895
19%
632
54%
632
27%
1207
March1st to 15thNight
42%
720
15%
2076
11%
720
47%
720
23%
1395
March16th to endNight
43%
768
18%
2046
12%
768
48%
768
26%
1349
April1st to 15thNight
46%
719
18%
1799
9%
719
49%
719
28%
1219
April16th to endNight
54%
720
22%
1800
11%
720
58%
720
38%
1088
May1st to 15thNight
54%
510
24%
1590
17%
510
60%
510
42%
800
May16th to endNight
64%
374
20%
1496
23%
374
67%
374
28%
783
June1st to 15thNight
70%
360
23%
1440
29%
360
75%
360
39%
653
June16th to endNight
81%
360
33%
1440
45%
360
85%
360
58%
521
July1st to 15thNight
92%
340
32%
1360
46%
340
93%
340
69%
436
July16th to endNight
92%
444
40%
1479
45%
417
93%
417
75%
502
August1st to 15thNight
88%
561
38%
1634
31%
558
90%
558
69%
700
August16th to endNight
88%
764
44%
1910
28%
764
88%
764
79%
863
September1st to 15thNight
85%
720
41%
1800
27%
720
88%
720
74%
843
September16th to endNight
79%
716
43%
1941
36%
716
83%
716
67%
888
October1st to 15thNight
66%
720
30%
2160
29%
720
73%
720
47%
1067
October16th to endNight
69%
768
35%
2307
34%
768
74%
768
48%
1151
November1st to 15thNight
58%
760
23%
2470
22%
760
64%
760
31%
1415
November16th to endNight
52%
780
22%
2648
20%
780
58%
780
30%
1482
December1st to 15thNight
49%
780
22%
2730
19%
780
56%
780
25%
1633
December16th to endNight
40%
832
23%
2912
17%
832
49%
832
21%
1854

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
6%6%23313346%59%
49041
Night
7%6%13323346%57%
48679
TransparencyDay
28%28%21%22%16%
48719
Night
29%29%22%21%13%
48502
SeeingDay
16%15%29%21%11%3
6155
Night
13%5%15%36%25%3
15622

By Month

Percentage Cloud Cover SW (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 15thDay
9%8%24425%45%8%43%
1552
16th to endDay
9%13%35%41345%7%41%
1755
February1st to 15thDay
9%9%3442345%8%44%
1584
16th to endDay
9%17%35%313347%39%
1579
March1st to 15thDay
9%14%5%5%424448%36%
1881
16th to endDay
9%14%2442345%6%40%
2177
April1st to 15thDay
10%13%3442346%8%38%
2149
16th to endDay
9%6%23323346%53%
2160
May1st to 15thDay
6%423313337%60%
2356
16th to endDay
10%5%2442435%6%50%
2615
June1st to 15thDay
6%324413335%60%
2520
16th to endDay
2111122480%
2520
July1st to 15thDay
11122384%
2520
16th to endDay
111112384%
2586
August1st to 15thDay
21111122381%
2316
16th to endDay
1112287%
2292
September1st to 15thDay
11111123479%
2160
16th to endDay
2211112226%74%
2018
October1st to 15thDay
6%312212335%66%
1800
16th to endDay
7%314323347%59%
1917
November1st to 15thDay
9%5%234345%5%8%48%
1719
16th to endDay
6%8%35%424447%47%
1641
December1st to 15thDay
10%8%36%42445%7%41%
1560
16th to endDay
12%9%36%5%2446%8%38%
1664
January1st to 15thNight
7%7%25%5%3445%7%45%
2716
16th to endNight
9%11%24424445%44%
2571
February1st to 15thNight
7%9%24435%46%8%43%
2269
16th to endNight
10%14%2421335%6%43%
1895
March1st to 15thNight
8%14%35%42446%7%37%
2076
16th to endNight
9%13%2332345%7%44%
2046
April1st to 15thNight
7%11%35%4245%5%7%41%
1799
16th to endNight
7%6%23414347%55%
1800
May1st to 15thNight
7%213313345%62%
1590
16th to endNight
9%5%23324446%53%
1496
June1st to 15thNight
7%212213347%63%
1440
16th to endNight
21121223377%
1440
July1st to 15thNight
11111122383%
1440
16th to endNight
11122484%
1580
August1st to 15thNight
2111223478%
1643
16th to endNight
11122384%
1910
September1st to 15thNight
111123480%
1800
16th to endNight
21111222478%
1941
October1st to 15thNight
6%1321323469%
2160
16th to endNight
6%2232345%7%62%
2307
November1st to 15thNight
10%5%2332345%8%49%
2470
16th to endNight
7%6%2342445%8%49%
2648
December1st to 15thNight
11%8%2442345%7%45%
2730
16th to endNight
12%11%35%42335%6%41%
2912

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 15thDay
40%413%25%13%1
1552
16th to endDay
43%310%20%14%7%
1755
February1st to 15thDay
40%213%23%16%2
1584
16th to endDay
46%211%26%10%2
1579
March1st to 15thDay
48%410%19%13%3
1881
16th to endDay
44%316%19%11%3
2177
April1st to 15thDay
44%313%22%14%1
2149
16th to endDay
33%212%27%18%4
2160
May1st to 15thDay
26%19%29%27%5%
2356
16th to endDay
35%210%26%19%4
2619
June1st to 15thDay
27%29%20%24%15%
2520
16th to endDay
10%318%40%25%
2520
July1st to 15thDay
7%1211%27%50%
2371
16th to endDay
8%1112%23%53%
2425
August1st to 15thDay
10%1213%29%43%
2300
16th to endDay
6%115%34%42%
2292
September1st to 15thDay
11%1213%35%36%
2160
16th to endDay
14%15%28%30%19%
2018
October1st to 15thDay
22%25%25%30%14%
1800
16th to endDay
27%29%23%24%13%
1917
November1st to 15thDay
35%212%26%16%5%
1719
16th to endDay
37%211%26%17%3
1641
December1st to 15thDay
42%39%23%20%1
1560
16th to endDay
44%410%20%17%2
1664
January1st to 15thNight
38%313%25%15%2
2716
16th to endNight
42%210%18%17%8%
2571
February1st to 15thNight
40%311%25%15%3
2281
16th to endNight
42%212%26%13%2
1895
March1st to 15thNight
46%313%18%13%4
2076
16th to endNight
40%5%15%21%12%3
2046
April1st to 15thNight
42%416%22%11%2
1799
16th to endNight
31%312%31%17%3
1800
May1st to 15thNight
25%114%27%24%6%
1591
16th to endNight
33%314%27%17%4
1496
June1st to 15thNight
22%415%21%22%14%
1440
16th to endNight
13%15%18%37%23%
1440
July1st to 15thNight
8%1211%29%47%
1360
16th to endNight
6%1212%24%52%
1479
August1st to 15thNight
11%1115%29%40%
1634
16th to endNight
7%1217%30%41%
1910
September1st to 15thNight
9%2313%36%35%
1800
16th to endNight
12%15%25%34%20%
1941
October1st to 15thNight
22%16%25%27%15%
2160
16th to endNight
22%111%26%27%10%
2307
November1st to 15thNight
34%411%27%16%5%
2470
16th to endNight
34%311%26%18%5%
2648
December1st to 15thNight
39%310%21%21%2
2730
16th to endNight
45%38%19%20%2
2912

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 15thDay
36%227%18%13%1
90
16th to endDay
31%13%22%18%12%1
258
February1st to 15thDay
27%13%23%26%8%
237
16th to endDay
30%15%26%22%5%
238
March1st to 15thDay
35%19%22%11%7%4
270
16th to endDay
30%19%28%15%5%
288
April1st to 15thDay
32%20%27%14%31
269
16th to endDay
27%21%28%16%5%
270
May1st to 15thDay
16%25%32%15%8%1
288
16th to endDay
18%15%26%18%14%5%
330
June1st to 15thDay
17%14%34%20%9%3
315
16th to endDay
5%19%33%21%15%4
315
July1st to 15thDay
48%43%26%9%6%
305
16th to endDay
13%44%23%11%6%
327
August1st to 15thDay
5%16%35%24%9%8%
315
16th to endDay
217%31%23%18%7%
332
September1st to 15thDay
213%30%30%17%5%
315
16th to endDay
8%16%33%22%14%3
315
October1st to 15thDay
11%17%29%24%13%4
315
16th to endDay
15%16%20%28%15%3
333
November1st to 15thDay
19%7%19%22%26%5%
135
16th to endDay
20%8%24%30%15%
109
December1st to 15thDay
25%7%25%21%8%11%
90
16th to endDay
15%9%19%27%25%3
96
January1st to 15thNight
16%5%21%40%14%2
780
16th to endNight
20%6%23%32%15%
788
February1st to 15thNight
19%7%19%39%14%
704
16th to endNight
23%6%18%36%13%1
632
March1st to 15thNight
24%9%17%29%17%1
720
16th to endNight
20%12%19%28%18%1
768
April1st to 15thNight
19%9%20%34%14%1
719
16th to endNight
14%9%17%35%19%4
720
May1st to 15thNight
10%7%22%32%25%1
511
16th to endNight
12%5%12%30%34%5%
375
June1st to 15thNight
8%312%33%36%3
360
16th to endNight
319%41%41%2
360
July1st to 15thNight
1237%54%3
340
16th to endNight
1431%54%7%
444
August1st to 15thNight
21335%49%7%
561
16th to endNight
17%41%43%4
764
September1st to 15thNight
217%35%44%8%
720
16th to endNight
4211%39%33%8%
716
October1st to 15thNight
10%6%12%36%29%4
720
16th to endNight
9%5%12%40%29%3
768
November1st to 15thNight
15%417%38%21%2
760
16th to endNight
16%7%19%37%17%
780
December1st to 15thNight
19%7%18%37%14%1
780
16th to endNight
24%6%23%34%10%
832
Page generated at 2018-01-21 09:19:28. Version ac04

Copyright 2018 A. Danko


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