Greater Napanee
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Greater Napanee clear sky chart from 2005-11-05 to 2017-12-01.

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
33%
15048
14%
47815
9%
15018
40%
15018
19%
33175

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
14%
720
9%
2506
3%
716
21%
716
8%
1958
January16th to endNight
21%
768
11%
2573
5%
768
29%
768
11%
1949
February1st to 15thNight
17%
703
10%
2287
3%
701
25%
701
12%
1762
February16th to endNight
22%
631
14%
1970
6%
631
32%
631
15%
1441
March1st to 15thNight
22%
720
15%
2052
8%
720
31%
720
18%
1512
March16th to endNight
31%
768
20%
2067
9%
768
39%
768
26%
1398
April1st to 15thNight
26%
718
16%
1796
5%
718
32%
718
23%
1293
April16th to endNight
35%
655
18%
1735
7%
655
42%
655
26%
1175
May1st to 15thNight
42%
386
16%
1466
15%
386
48%
386
19%
946
May16th to endNight
43%
374
16%
1497
15%
374
54%
374
22%
903
June1st to 15thNight
43%
360
12%
1440
12%
360
52%
360
19%
911
June16th to endNight
48%
360
10%
1440
13%
360
54%
360
21%
878
July1st to 15thNight
58%
340
16%
1360
22%
340
64%
340
30%
732
July16th to endNight
60%
376
16%
1418
21%
354
63%
354
29%
761
August1st to 15thNight
59%
521
15%
1592
11%
519
62%
519
31%
964
August16th to endNight
59%
691
23%
1837
12%
691
64%
691
39%
1096
September1st to 15thNight
52%
720
19%
1800
10%
720
56%
720
35%
1167
September16th to endNight
53%
717
24%
1973
16%
717
58%
717
32%
1237
October1st to 15thNight
34%
720
16%
2160
12%
720
41%
720
20%
1511
October16th to endNight
24%
768
12%
2349
5%
768
32%
768
14%
1737
November1st to 15thNight
32%
760
18%
2547
14%
760
40%
760
19%
1718
November16th to endNight
23%
780
12%
2730
7%
780
31%
780
11%
2034
December1st to 15thNight
16%
724
7%
2532
3%
724
21%
724
9%
1960
December16th to endNight
13%
768
8%
2688
2%
768
21%
768
9%
2132

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
16%8%36%5%3445%7%35%
48621
Night
17%8%35%5%3445%6%35%
47985
Cloud CoverDay
16%7%36%5%3445%7%35%
48631
Night
17%8%35%5%2445%6%35%
47990
TransparencyDay
47%7%13%20%10%1
48309
Night
48%6%12%20%11%1
47815
SeeingDay
19%8%27%25%13%4
5705
Night
21%9%29%26%11%1
15050

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 15thDay
21%13%35%5%24446%28%
1432
16th to endDay
13%15%5%9%7%47%5%45%22%
1650
February1st to 15thDay
15%12%5%12%8%45%445%21%
1575
16th to endDay
19%11%46%6%35%44428%
1502
March1st to 15thDay
16%11%38%8%45%345%27%
1896
16th to endDay
16%8%26%6%3433440%
2157
April1st to 15thDay
21%9%36%5%33335%34%
2152
16th to endDay
18%6%26%433446%38%
2235
May1st to 15thDay
15%8%36%5%35%447%34%
2484
16th to endDay
13%5%245%35%46%9%39%
2618
June1st to 15thDay
19%5%35%5%3446%7%34%
2520
16th to endDay
14%6%25%425%5%5%9%37%
2520
July1st to 15thDay
10%4245%35%46%9%43%
2520
16th to endDay
10%425%6%35%5%7%9%38%
2654
August1st to 15thDay
9%5%25%6%35%5%7%9%39%
2355
16th to endDay
12%4134345%6%8%45%
2351
September1st to 15thDay
14%5%14433447%45%
2160
16th to endDay
13%6%2432345%7%46%
1986
October1st to 15thDay
19%6%24435%5%46%36%
1800
16th to endDay
25%7%25%6%25%446%28%
1875
November1st to 15thDay
15%8%25%5%35%5%6%6%34%
1641
16th to endDay
21%9%46%6%34447%27%
1560
December1st to 15thDay
21%13%5%7%6%35%5%45%21%
1442
16th to endDay
23%13%5%7%5%2443422%
1536
January1st to 15thNight
22%12%47%7%35%435%23%
2506
16th to endNight
15%13%5%7%6%35%5%5%5%25%
2573
February1st to 15thNight
16%12%5%9%6%3444427%
2285
16th to endNight
18%9%36%7%3445%7%29%
1970
March1st to 15thNight
20%8%37%5%34335%32%
2040
16th to endNight
16%7%45%423445%42%
2067
April1st to 15thNight
22%6%46%324346%35%
1796
16th to endNight
16%5%15%5%245%45%42%
1735
May1st to 15thNight
18%6%35%43345%6%38%
1466
16th to endNight
11%5%245%346%5%7%43%
1495
June1st to 15thNight
15%6%25%4346%6%8%37%
1440
16th to endNight
13%425%5%35%45%8%40%
1440
July1st to 15thNight
7%314435%5%5%7%50%
1440
16th to endNight
8%4133235%7%9%48%
1514
August1st to 15thNight
10%4244245%5%10%45%
1602
16th to endNight
7%41443446%8%51%
1837
September1st to 15thNight
14%42332335%8%47%
1800
16th to endNight
15%31332345%6%49%
1973
October1st to 15thNight
19%6%25%5%34345%37%
2160
16th to endNight
22%7%36%5%24446%30%
2349
November1st to 15thNight
19%7%25%424447%37%
2547
16th to endNight
23%8%35%425%5%5%6%29%
2730
December1st to 15thNight
22%13%36%5%34346%26%
2532
16th to endNight
22%12%5%7%5%35%5%46%21%
2688

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
21%13%35%5%25%445%28%
1432
16th to endDay
13%14%6%7%7%46%5%5%5%22%
1650
February1st to 15thDay
15%11%5%12%7%45%445%21%
1575
16th to endDay
18%12%5%6%5%35%445%28%
1502
March1st to 15thDay
17%10%48%7%35%445%27%
1907
16th to endDay
16%7%36%5%34345%39%
2156
April1st to 15thDay
21%9%36%5%23345%34%
2152
16th to endDay
18%6%36%5%33447%37%
2235
May1st to 15thDay
15%7%36%5%35%45%7%35%
2484
16th to endDay
13%5%35%5%345%6%8%39%
2618
June1st to 15thDay
18%6%25%6%25%45%7%34%
2520
16th to endDay
13%5%25%425%5%6%8%38%
2520
July1st to 15thDay
9%4245%35%5%7%8%43%
2520
16th to endDay
9%425%5%35%6%7%10%39%
2654
August1st to 15thDay
9%5%25%5%45%5%7%8%40%
2355
16th to endDay
11%3144245%6%9%45%
2351
September1st to 15thDay
13%415%4335%47%45%
2160
16th to endDay
13%5%2442445%6%46%
1986
October1st to 15thDay
19%5%25%425%5%47%36%
1800
16th to endDay
25%7%25%5%345%5%5%28%
1875
November1st to 15thDay
16%8%345%35%46%6%34%
1641
16th to endDay
21%9%37%5%34447%28%
1560
December1st to 15thDay
21%13%48%5%345%46%21%
1442
16th to endDay
23%13%5%7%5%3444422%
1536
January1st to 15thNight
22%12%47%7%35%435%23%
2506
16th to endNight
16%12%48%6%35%5%5%5%26%
2573
February1st to 15thNight
15%13%5%9%6%35%5%45%26%
2278
16th to endNight
18%9%36%7%3346%6%29%
1970
March1st to 15thNight
21%8%36%6%34345%32%
2052
16th to endNight
16%7%35%42235%442%
2067
April1st to 15thNight
22%7%35%324446%35%
1796
16th to endNight
16%5%245%3445%5%41%
1735
May1st to 15thNight
18%6%35%42435%6%38%
1466
16th to endNight
11%5%35%4346%5%6%43%
1495
June1st to 15thNight
15%5%35%5%245%6%8%36%
1440
16th to endNight
13%425%6%35%45%9%39%
1440
July1st to 15thNight
7%314445%45%9%49%
1440
16th to endNight
8%4144235%7%9%48%
1514
August1st to 15thNight
10%32442447%8%45%
1602
16th to endNight
7%32442446%8%50%
1837
September1st to 15thNight
14%41432335%8%47%
1800
16th to endNight
15%31341445%6%49%
1973
October1st to 15thNight
19%7%26%5%34346%36%
2160
16th to endNight
23%6%35%6%34447%30%
2349
November1st to 15thNight
19%7%25%42445%7%37%
2547
16th to endNight
23%8%35%5%3445%6%28%
2730
December1st to 15thNight
22%14%36%5%24446%26%
2532
16th to endNight
23%12%47%5%35%45%6%21%
2688

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
59%6%11%16%5%
1433
16th to endDay
63%7%8%11%8%
1650
February1st to 15thDay
64%6%8%14%4
1577
16th to endDay
58%6%11%13%9%
1502
March1st to 15thDay
58%5%13%15%5%1
1907
16th to endDay
47%5%8%20%14%3
2157
April1st to 15thDay
51%49%19%11%3
2152
16th to endDay
45%5%9%20%15%2
2235
May1st to 15thDay
46%7%11%19%12%2
2484
16th to endDay
39%8%15%22%12%1
2622
June1st to 15thDay
47%7%14%20%10%
2520
16th to endDay
40%7%15%21%13%
2520
July1st to 15thDay
33%7%14%29%13%
2371
16th to endDay
38%8%19%23%9%
2487
August1st to 15thDay
38%8%18%23%11%1
2341
16th to endDay
33%7%16%30%11%
2351
September1st to 15thDay
36%6%16%26%13%
2160
16th to endDay
36%8%12%30%12%
1986
October1st to 15thDay
46%6%13%22%10%
1800
16th to endDay
55%6%14%17%5%
1875
November1st to 15thDay
47%9%13%18%9%
1641
16th to endDay
55%7%13%15%7%
1560
December1st to 15thDay
63%7%13%11%3
1442
16th to endDay
65%6%9%12%5%
1536
January1st to 15thNight
63%6%10%13%5%
2506
16th to endNight
58%6%9%15%8%
2573
February1st to 15thNight
60%5%11%16%5%
2287
16th to endNight
53%6%11%18%8%
1970
March1st to 15thNight
54%49%21%7%
2052
16th to endNight
43%5%10%19%17%2
2067
April1st to 15thNight
49%49%19%15%2
1796
16th to endNight
41%6%11%18%18%3
1735
May1st to 15thNight
46%5%10%18%15%3
1466
16th to endNight
39%7%12%21%15%2
1497
June1st to 15thNight
43%7%14%20%13%
1440
16th to endNight
40%7%15%19%15%1
1440
July1st to 15thNight
30%6%12%28%20%1
1360
16th to endNight
30%7%14%29%16%1
1418
August1st to 15thNight
33%8%17%27%13%
1592
16th to endNight
29%6%14%33%14%1
1837
September1st to 15thNight
34%6%15%29%12%1
1800
16th to endNight
35%6%11%31%15%
1973
October1st to 15thNight
48%5%11%22%11%
2160
16th to endNight
54%7%14%16%6%
2349
November1st to 15thNight
47%6%13%19%12%1
2547
16th to endNight
55%8%12%16%5%
2730
December1st to 15thNight
59%8%13%15%3
2532
16th to endNight
64%6%11%11%4
2688

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
18%28%26%18%6%1
60
16th to endDay
31%13%33%18%3
83
February1st to 15thDay
23%23%40%12%1
90
16th to endDay
34%14%31%15%4
161
March1st to 15thDay
26%12%28%25%6%
270
16th to endDay
26%9%34%18%10%1
288
April1st to 15thDay
25%15%30%16%11%1
270
16th to endDay
18%8%38%17%12%4
270
May1st to 15thDay
25%428%26%10%5%
288
16th to endDay
16%5%32%26%13%4
331
June1st to 15thDay
19%6%29%31%10%3
315
16th to endDay
15%5%28%32%15%2
315
July1st to 15thDay
11%319%39%18%7%
305
16th to endDay
13%226%33%17%7%
326
August1st to 15thDay
11%221%33%23%7%
313
16th to endDay
14%418%29%20%11%
332
September1st to 15thDay
14%426%21%20%13%
315
16th to endDay
14%5%23%22%21%11%
314
October1st to 15thDay
23%6%29%20%14%4
315
16th to endDay
26%17%25%23%7%
325
November1st to 15thDay
20%10%28%28%10%1
205
16th to endDay
23%15%36%15%7%1
90
December1st to 15thDay
15%25%28%23%8%
60
16th to endDay
39%28%23%9%
64
January1st to 15thNight
28%16%32%16%5%
720
16th to endNight
23%12%34%24%5%
768
February1st to 15thNight
22%15%38%19%4
704
16th to endNight
21%11%36%23%6%
631
March1st to 15thNight
26%10%33%26%2
720
16th to endNight
20%7%34%25%10%1
768
April1st to 15thNight
25%9%34%24%6%
718
16th to endNight
19%7%32%25%12%1
655
May1st to 15thNight
22%426%33%12%1
386
16th to endNight
10%433%35%13%2
375
June1st to 15thNight
16%329%31%17%1
360
16th to endNight
15%324%40%15%
360
July1st to 15thNight
6%225%39%23%2
340
16th to endNight
9%123%42%21%1
376
August1st to 15thNight
12%217%38%24%4
521
16th to endNight
8%223%37%25%3
691
September1st to 15thNight
15%422%29%24%3
720
16th to endNight
16%422%25%23%6%
717
October1st to 15thNight
23%9%28%20%15%2
720
16th to endNight
27%12%28%25%6%
768
November1st to 15thNight
24%9%29%24%11%1
760
16th to endNight
29%15%27%18%9%
780
December1st to 15thNight
29%18%32%16%3
724
16th to endNight
31%11%35%16%3
768
Page generated at 2017-12-02 09:14:15. Version ac04

Copyright 2017 A. Danko


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