Norborne
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Norborne clear sky chart from 2005-11-05 to 2019-06-02.

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
43%
18249
22%
53884
14%
18202
50%
18202
30%
33394

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
32%
1050
21%
2745
9%
1045
41%
1045
29%
1791
January16th to endNight
27%
1120
22%
2912
7%
1120
36%
1120
28%
1948
February1st to 15thNight
26%
1030
14%
2678
5%
1026
31%
1026
21%
1930
February16th to endNight
27%
796
20%
2266
6%
796
37%
796
26%
1496
March1st to 15thNight
33%
630
22%
2310
13%
630
44%
630
23%
1398
March16th to endNight
28%
672
13%
2464
10%
672
35%
672
16%
1698
April1st to 15thNight
34%
629
21%
2122
14%
629
46%
629
26%
1267
April16th to endNight
36%
624
20%
2028
15%
624
48%
624
24%
1301
May1st to 15thNight
43%
629
18%
1889
15%
629
49%
629
25%
1242
May16th to endNight
49%
659
19%
1818
13%
657
54%
657
32%
1156
June1st to 15thNight
64%
588
23%
1568
14%
588
68%
588
44%
908
June16th to endNight
66%
585
22%
1560
13%
585
69%
585
47%
873
July1st to 15thNight
72%
555
20%
1553
17%
555
72%
555
42%
883
July16th to endNight
74%
612
24%
1738
22%
579
78%
579
45%
909
August1st to 15thNight
77%
575
25%
1717
29%
572
79%
572
43%
922
August16th to endNight
73%
621
24%
1999
30%
621
74%
621
39%
1070
September1st to 15thNight
65%
585
27%
1950
30%
585
68%
585
35%
1091
September16th to endNight
63%
611
28%
2164
24%
611
70%
611
36%
1127
October1st to 15thNight
42%
780
25%
2340
18%
780
47%
780
32%
1410
October16th to endNight
42%
832
28%
2496
16%
832
51%
832
35%
1422
November1st to 15thNight
41%
846
26%
2551
15%
846
53%
846
31%
1511
November16th to endNight
33%
1050
23%
2940
9%
1050
45%
1050
31%
1842
December1st to 15thNight
30%
1050
18%
2940
8%
1050
38%
1050
24%
1987
December16th to endNight
27%
1120
18%
3136
7%
1120
37%
1120
21%
2212

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
12%6%35%5%2445%7%42%
54442
Night
12%6%24424446%47%
54076
TransparencyDay
40%6%13%24%13%1
54138
Night
36%5%12%25%16%2
53885
SeeingDay
14%6%25%28%19%5%
8141
Night
15%7%29%32%14%1
18250

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%7%37%6%24436%41%
1850
16th to endDay
14%10%5%7%5%34435%36%
2016
February1st to 15thDay
15%10%47%5%24347%33%
1845
16th to endDay
13%10%47%5%23345%38%
1788
March1st to 15thDay
13%9%46%5%24447%36%
2310
16th to endDay
21%10%45%5%34445%29%
2462
April1st to 15thDay
16%8%25%424446%41%
2486
16th to endDay
20%7%36%434347%34%
2535
May1st to 15thDay
16%7%46%5%34446%35%
2721
16th to endDay
12%6%25%6%35%45%8%38%
2998
June1st to 15thDay
7%425%5%35%46%8%45%
2745
16th to endDay
6%3145%25%47%10%47%
2730
July1st to 15thDay
7%4145%25%46%9%47%
2648
16th to endDay
6%324425%5%6%7%50%
2674
August1st to 15thDay
7%4245%25%47%9%47%
2486
16th to endDay
8%424425%6%5%8%46%
2553
September1st to 15thDay
12%324423447%50%
2340
16th to endDay
8%4144345%48%50%
2110
October1st to 15thDay
16%5%24423346%47%
1950
16th to endDay
13%5%14322345%51%
2080
November1st to 15thDay
12%7%24323336%49%
1963
16th to endDay
19%6%34311235%46%
1680
December1st to 15thDay
13%11%37%5%23346%38%
1680
16th to endDay
14%9%48%433346%35%
1792
January1st to 15thNight
10%7%25%5%34446%45%
2745
16th to endNight
10%8%36%5%24446%43%
2912
February1st to 15thNight
13%9%46%5%3445%5%36%
2668
16th to endNight
14%8%36%323346%44%
2266
March1st to 15thNight
14%7%34424346%44%
2310
16th to endNight
20%8%36%5%34346%33%
2464
April1st to 15thNight
12%6%24423436%48%
2122
16th to endNight
17%6%34423436%42%
2028
May1st to 15thNight
13%5%25%435%45%7%41%
1889
16th to endNight
12%42442435%8%45%
1816
June1st to 15thNight
5%31343345%11%53%
1568
16th to endNight
3213335%46%9%56%
1560
July1st to 15thNight
7%3134135%6%8%54%
1639
16th to endNight
411442446%11%53%
1846
August1st to 15thNight
42233235%6%8%56%
1727
16th to endNight
7%41342445%6%56%
1999
September1st to 15thNight
10%423423347%52%
1950
16th to endNight
7%41242435%7%55%
2164
October1st to 15thNight
15%5%13412345%51%
2340
16th to endNight
12%5%2331233456%
2496
November1st to 15thNight
13%5%13323436%52%
2551
16th to endNight
14%6%33323245%49%
2940
December1st to 15thNight
15%8%35%423445%41%
2940
16th to endNight
17%9%37%5%2333437%
3136

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
45%5%10%22%14%
1851
16th to endDay
50%414%19%8%
2016
February1st to 15thDay
50%6%14%20%7%1
1846
16th to endDay
48%414%18%13%1
1788
March1st to 15thDay
48%5%11%22%9%1
2310
16th to endDay
56%5%11%19%6%
2464
April1st to 15thDay
44%5%13%23%11%
2486
16th to endDay
50%5%12%20%10%
2535
May1st to 15thDay
49%6%12%21%8%
2721
16th to endDay
42%8%15%22%10%1
3002
June1st to 15thDay
34%7%14%28%14%1
2745
16th to endDay
30%7%18%28%14%1
2730
July1st to 15thDay
32%8%15%26%12%4
2505
16th to endDay
28%8%14%31%15%
2519
August1st to 15thDay
31%7%15%27%16%
2472
16th to endDay
32%8%14%23%16%4
2553
September1st to 15thDay
32%6%11%23%20%5%
2340
16th to endDay
31%6%11%30%17%2
2110
October1st to 15thDay
38%410%24%17%4
1950
16th to endDay
34%410%26%20%4
2080
November1st to 15thDay
37%412%23%19%3
1963
16th to endDay
41%310%29%15%
1680
December1st to 15thDay
47%5%14%22%9%
1680
16th to endDay
50%412%20%10%1
1792
January1st to 15thNight
39%413%24%16%1
2745
16th to endNight
40%5%14%23%13%1
2912
February1st to 15thNight
48%6%12%19%11%1
2678
16th to endNight
42%5%11%21%17%2
2266
March1st to 15thNight
40%5%10%25%15%3
2310
16th to endNight
51%6%11%20%9%1
2464
April1st to 15thNight
37%410%27%17%2
2122
16th to endNight
42%5%9%24%15%1
2028
May1st to 15thNight
40%8%15%22%13%
1890
16th to endNight
35%6%14%26%14%1
1818
June1st to 15thNight
25%6%15%30%19%2
1568
16th to endNight
22%6%15%32%19%3
1560
July1st to 15thNight
26%5%12%34%17%3
1553
16th to endNight
21%6%16%35%18%1
1738
August1st to 15thNight
22%7%14%30%21%2
1717
16th to endNight
26%5%11%26%23%6%
1999
September1st to 15thNight
30%5%11%22%23%7%
1950
16th to endNight
27%5%11%31%20%3
2164
October1st to 15thNight
35%48%24%20%6%
2340
16th to endNight
31%38%26%23%5%
2496
November1st to 15thNight
34%411%22%21%6%
2551
16th to endNight
37%410%28%17%1
2940
December1st to 15thNight
44%5%13%23%12%
2940
16th to endNight
49%411%19%11%2
3136

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
21%13%34%22%7%
180
16th to endDay
21%12%43%17%4
192
February1st to 15thDay
23%17%40%15%3
180
16th to endDay
18%18%40%13%8%
159
March1st to 15thDay
24%11%41%20%1
180
16th to endDay
33%13%26%20%6%
192
April1st to 15thDay
20%13%32%24%7%
365
16th to endDay
22%8%32%23%11%1
427
May1st to 15thDay
17%9%31%28%11%1
618
16th to endDay
15%5%29%27%17%5%
677
June1st to 15thDay
7%320%37%23%7%
576
16th to endDay
6%327%38%19%4
570
July1st to 15thDay
9%213%31%29%12%
550
16th to endDay
7%11%32%38%8%
595
August1st to 15thDay
6%12%34%36%8%
549
16th to endDay
10%115%29%32%9%
465
September1st to 15thDay
12%113%31%33%8%
375
16th to endDay
5%324%33%20%11%
187
October1st to 15thDay
19%6%34%26%8%3
180
16th to endDay
13%11%35%30%8%
192
November1st to 15thDay
21%8%23%25%15%6%
180
16th to endDay
31%8%26%21%12%
180
December1st to 15thDay
18%15%38%15%8%3
180
16th to endDay
21%16%38%19%31
192
January1st to 15thNight
14%11%36%28%8%
1050
16th to endNight
15%10%41%29%4
1120
February1st to 15thNight
16%11%39%28%4
1030
16th to endNight
20%11%37%26%4
796
March1st to 15thNight
17%9%35%30%5%
630
16th to endNight
23%9%35%25%7%
672
April1st to 15thNight
15%12%35%29%6%
629
16th to endNight
20%7%32%30%9%
624
May1st to 15thNight
15%6%28%36%12%1
630
16th to endNight
14%326%33%18%2
659
June1st to 15thNight
6%121%47%20%2
588
16th to endNight
3124%47%20%2
585
July1st to 15thNight
9%10%45%30%3
555
16th to endNight
5%12%41%38%1
612
August1st to 15thNight
49%42%40%2
575
16th to endNight
8%11%40%33%4
621
September1st to 15thNight
11%114%39%28%4
585
16th to endNight
8%219%36%27%4
611
October1st to 15thNight
18%5%28%28%16%2
780
16th to endNight
14%8%32%31%12%
832
November1st to 15thNight
15%10%29%32%10%
846
16th to endNight
18%10%35%27%8%
1050
December1st to 15thNight
20%10%34%27%6%
1050
16th to endNight
22%9%34%29%4
1120
Page generated at 2019-06-02 18:43:10. Version ac04

Copyright 2019 A. Danko


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