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 2017-09-23.

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
55%
15555
23%
47034
17%
15511
62%
15511
30%
28802

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
34%
720
22%
2327
11%
716
48%
716
24%
1418
January16th to endNight
36%
768
24%
2345
14%
768
46%
768
24%
1490
February1st to 15thNight
40%
704
27%
2109
14%
700
52%
700
29%
1271
February16th to endNight
34%
631
25%
1893
11%
631
46%
631
27%
1172
March1st to 15thNight
44%
720
27%
2061
15%
720
53%
720
35%
1216
March16th to endNight
46%
768
25%
2112
15%
768
53%
768
35%
1265
April1st to 15thNight
49%
659
26%
1917
19%
659
56%
659
35%
1110
April16th to endNight
57%
540
30%
1770
23%
540
67%
540
39%
939
May1st to 15thNight
61%
539
26%
1619
19%
539
68%
539
41%
897
May16th to endNight
74%
561
23%
1682
19%
561
77%
561
36%
1000
June1st to 15thNight
74%
540
15%
1620
14%
540
74%
540
28%
1038
June16th to endNight
74%
540
14%
1620
12%
540
75%
540
25%
1085
July1st to 15thNight
80%
510
11%
1530
11%
510
80%
510
31%
975
July16th to endNight
79%
564
11%
1595
12%
531
80%
531
26%
1066
August1st to 15thNight
77%
539
10%
1765
13%
536
78%
536
23%
1182
August16th to endNight
72%
573
14%
1910
17%
573
72%
573
21%
1317
September1st to 15thNight
63%
718
12%
1978
11%
718
64%
718
20%
1423
September16th to endNight
62%
689
21%
1903
17%
689
66%
689
27%
1260
October1st to 15thNight
62%
660
32%
1815
25%
660
69%
660
41%
1043
October16th to endNight
57%
704
33%
2075
29%
704
64%
704
38%
1171
November1st to 15thNight
53%
700
31%
2212
26%
700
63%
700
37%
1200
November16th to endNight
47%
720
29%
2340
22%
720
58%
720
34%
1270
December1st to 15thNight
43%
720
25%
2340
20%
720
52%
720
29%
1379
December16th to endNight
40%
768
22%
2496
18%
768
49%
768
22%
1615

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
10%5%25%6%36%5%6%7%39%
47860
Night
9%42442446%8%46%
47237
TransparencyDay
40%8%11%15%15%7%
47561
Night
33%8%13%18%17%9%
47040
SeeingDay
11%5%16%23%24%18%
5450
Night
11%5%20%30%25%5%
15558

By Month

Percentage Cloud Cover SE (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
12%6%26%5%3345%7%42%
1611
16th to endDay
15%5%2442345%6%44%
1878
February1st to 15thDay
14%6%24324346%47%
1750
16th to endDay
13%6%24423336%48%
1580
March1st to 15thDay
9%5%24434447%48%
1898
16th to endDay
11%5%24434445%49%
2111
April1st to 15thDay
10%5%345%34446%47%
2040
16th to endDay
7%415%5%35%45%7%50%
2189
May1st to 15thDay
6%415%5%345%7%9%46%
2331
16th to endDay
6%435%8%46%6%6%9%39%
2431
June1st to 15thDay
9%5%36%7%5%8%7%8%9%27%
2340
16th to endDay
6%5%36%9%5%10%8%8%9%27%
2340
July1st to 15thDay
7%5%37%9%6%11%8%8%10%21%
2340
16th to endDay
8%436%10%5%8%8%8%10%23%
2465
August1st to 15thDay
9%6%310%10%5%9%9%7%8%18%
2180
16th to endDay
11%7%48%7%47%6%7%9%24%
2280
September1st to 15thDay
9%6%37%7%5%7%7%7%9%26%
1980
16th to endDay
12%5%26%6%35%6%6%8%37%
1894
October1st to 15thDay
8%5%25%5%34446%49%
1815
16th to endDay
8%324423445%55%
1796
November1st to 15thDay
8%413324446%57%
1643
16th to endDay
10%414423446%53%
1620
December1st to 15thDay
12%5%245%24446%46%
1620
16th to endDay
17%7%26%5%24346%37%
1728
January1st to 15thNight
12%5%25%5%2345%6%44%
2327
16th to endNight
15%6%235%24446%44%
2345
February1st to 15thNight
14%424423335%50%
2103
16th to endNight
14%5%24423346%48%
1893
March1st to 15thNight
8%425%42335%8%50%
2061
16th to endNight
9%414323447%53%
2112
April1st to 15thNight
8%424424447%52%
1917
16th to endNight
6%213424447%56%
1770
May1st to 15thNight
6%22342445%10%52%
1619
16th to endNight
33135%35%5%8%9%49%
1682
June1st to 15thNight
5%3245%36%7%7%14%37%
1620
16th to endNight
5%326%6%36%7%9%12%35%
1620
July1st to 15thNight
5%3235%35%6%9%13%40%
1620
16th to endNight
43245%37%7%11%13%35%
1703
August1st to 15thNight
5%4245%46%8%9%15%31%
1776
16th to endNight
7%5%26%5%46%6%8%12%33%
1910
September1st to 15thNight
9%5%36%7%37%6%7%11%31%
1978
16th to endNight
7%5%25%6%36%5%7%9%39%
1903
October1st to 15thNight
5%324323348%55%
1815
16th to endNight
7%425%32433458%
2075
November1st to 15thNight
7%42442335%7%55%
2212
16th to endNight
9%424323346%55%
2340
December1st to 15thNight
11%5%245%24347%48%
2340
16th to endNight
16%6%35%424446%41%
2496

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
41%5%9%14%17%12%
1612
16th to endDay
39%48%15%19%12%
1878
February1st to 15thDay
38%36%15%22%13%
1752
16th to endDay
37%47%14%25%11%
1580
March1st to 15thDay
33%5%8%17%24%9%
1898
16th to endDay
36%410%18%18%11%
2112
April1st to 15thDay
38%5%7%16%19%12%
2040
16th to endDay
32%5%10%21%18%11%
2189
May1st to 15thDay
32%8%10%17%20%9%
2331
16th to endDay
39%8%14%19%14%4
2435
June1st to 15thDay
47%12%15%18%5%
2340
16th to endDay
47%13%16%14%6%1
2340
July1st to 15thDay
50%15%19%12%2
2201
16th to endDay
47%17%19%11%3
2310
August1st to 15thDay
56%14%15%9%3
2167
16th to endDay
51%13%16%12%41
2280
September1st to 15thDay
48%13%16%12%8%2
1980
16th to endDay
42%7%14%16%13%6%
1894
October1st to 15thDay
34%6%8%15%21%13%
1815
16th to endDay
30%47%12%27%17%
1796
November1st to 15thDay
27%47%18%26%15%
1643
16th to endDay
31%47%18%21%16%
1620
December1st to 15thDay
38%410%17%19%8%
1620
16th to endDay
47%5%7%17%13%8%
1728
January1st to 15thNight
38%5%9%13%20%12%
2327
16th to endNight
40%5%6%12%22%12%
2345
February1st to 15thNight
36%36%15%21%16%
2112
16th to endNight
37%5%6%15%18%16%
1893
March1st to 15thNight
31%49%21%22%9%
2061
16th to endNight
29%6%10%18%22%11%
2112
April1st to 15thNight
31%49%17%24%12%
1917
16th to endNight
25%5%10%26%20%11%
1770
May1st to 15thNight
25%6%13%19%22%11%
1620
16th to endNight
25%11%16%23%16%6%
1684
June1st to 15thNight
32%13%21%22%9%1
1620
16th to endNight
35%13%20%19%9%1
1620
July1st to 15thNight
29%14%30%22%2
1530
16th to endNight
31%17%28%17%4
1595
August1st to 15thNight
34%16%29%16%2
1765
16th to endNight
38%15%21%17%5%1
1910
September1st to 15thNight
42%14%17%13%10%1
1978
16th to endNight
37%10%15%15%14%6%
1903
October1st to 15thNight
26%6%9%20%20%15%
1815
16th to endNight
30%35%14%25%21%
2075
November1st to 15thNight
28%46%19%24%16%
2212
16th to endNight
29%49%16%20%19%
2340
December1st to 15thNight
36%410%19%22%7%
2340
16th to endNight
42%5%7%20%13%8%
2496

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
14%16%37%16%10%4
90
16th to endDay
21%20%30%20%6%
96
February1st to 15thDay
10%24%38%16%8%1
90
16th to endDay
13%18%39%22%6%
81
March1st to 15thDay
6%17%35%29%11%
188
16th to endDay
12%7%29%28%19%2
288
April1st to 15thDay
14%10%23%30%19%2
270
16th to endDay
6%423%33%24%7%
270
May1st to 15thDay
11%419%31%20%13%
288
16th to endDay
9%13%26%28%21%
331
June1st to 15thDay
15%17%19%29%25%
315
16th to endDay
8%5%21%27%36%
315
July1st to 15thDay
7%311%30%46%
305
16th to endDay
6%5%15%30%41%
326
August1st to 15thDay
12%420%27%34%
313
16th to endDay
9%6%17%31%34%
332
September1st to 15thDay
17%29%17%29%23%
315
16th to endDay
14%28%24%32%16%
283
October1st to 15thDay
10%414%38%23%7%
255
16th to endDay
7%6%22%30%26%5%
272
November1st to 15thDay
12%434%24%17%5%
151
16th to endDay
6%7%43%23%12%6%
90
December1st to 15thDay
13%14%33%25%12%1
90
16th to endDay
27%10%21%26%13%1
96
January1st to 15thNight
15%13%31%27%10%1
720
16th to endNight
17%12%30%29%9%
768
February1st to 15thNight
16%12%27%34%9%
704
16th to endNight
15%12%34%33%4
631
March1st to 15thNight
11%10%29%36%11%
720
16th to endNight
12%8%28%32%16%
768
April1st to 15thNight
11%6%27%39%15%
659
16th to endNight
8%227%34%25%2
540
May1st to 15thNight
7%221%36%27%3
540
16th to endNight
4112%36%38%6%
563
June1st to 15thNight
6%7%33%42%10%
540
16th to endNight
6%5%27%43%15%
540
July1st to 15thNight
6%218%51%19%
510
16th to endNight
5%420%49%18%
564
August1st to 15thNight
6%316%54%18%
539
16th to endNight
10%5%19%43%20%
573
September1st to 15thNight
12%8%26%37%14%
718
16th to endNight
9%114%35%33%5%
689
October1st to 15thNight
8%219%34%32%3
660
16th to endNight
9%6%20%33%27%2
704
November1st to 15thNight
8%5%26%36%21%2
700
16th to endNight
11%8%29%32%17%
720
December1st to 15thNight
13%8%29%31%16%
720
16th to endNight
19%10%24%27%16%1
768
Page generated at 2017-09-24 09:15:50. Version ac04

Copyright 2017 A. Danko


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