Daniel's Harbour
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Daniel's Harbour clear sky chart from 2005-11-05 to 2017-11-30.

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
17%
15360
5%
47684
2%
15316
19%
15316
7%
40560

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
6%
747
2%
2580
0%
746
8%
746
1%
2431
January16th to endNight
10%
800
3%
2688
2%
800
11%
800
2%
2515
February1st to 15thNight
9%
726
2%
2429
1%
725
10%
725
2%
2275
February16th to endNight
15%
631
2%
1922
1%
631
17%
631
4%
1697
March1st to 15thNight
15%
720
7%
2149
3%
716
18%
716
7%
1854
March16th to endNight
14%
612
8%
2010
3%
612
20%
612
6%
1680
April1st to 15thNight
20%
539
7%
1793
5%
539
23%
539
6%
1498
April16th to endNight
20%
540
11%
1580
4%
540
26%
540
11%
1208
May1st to 15thNight
28%
540
8%
1440
3%
540
31%
540
15%
1080
May16th to endNight
21%
561
5%
1371
2%
560
23%
560
12%
1119
June1st to 15thNight
24%
540
2%
1260
1%
540
25%
540
13%
1034
June16th to endNight
25%
467
1%
1187
1%
467
26%
467
14%
920
July1st to 15thNight
22%
510
2%
1208
1%
510
23%
510
17%
950
July16th to endNight
28%
565
4%
1419
2%
532
31%
532
14%
1114
August1st to 15thNight
32%
539
6%
1429
2%
535
34%
535
16%
1095
August16th to endNight
30%
573
8%
1756
4%
573
34%
573
14%
1320
September1st to 15thNight
24%
540
7%
1806
5%
540
29%
540
11%
1375
September16th to endNight
16%
538
8%
1980
4%
538
22%
538
8%
1532
October1st to 15thNight
18%
677
7%
2144
4%
677
21%
677
8%
1743
October16th to endNight
17%
816
6%
2496
3%
816
20%
816
7%
2135
November1st to 15thNight
11%
805
5%
2541
1%
805
14%
805
5%
2204
November16th to endNight
9%
824
4%
2916
2%
824
11%
824
3%
2595
December1st to 15thNight
6%
750
2%
2700
0%
750
9%
750
2%
2505
December16th to endNight
9%
800
2%
2880
2%
800
10%
800
2%
2681

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
24%13%47%6%34445%21%
48691
Night
24%15%6%9%8%3433416%
47858
TransparencyDay
66%5%10%13%4
48371
Night
73%48%10%2
47696
SeeingDay
29%21%21%16%8%2
8303
Night
29%25%19%16%7%1
15365

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
17%22%10%17%10%442324
1357
16th to endDay
15%22%8%13%18%5%5%2114
1536
February1st to 15thDay
13%18%7%12%14%7%8%4436%
1429
16th to endDay
14%22%7%10%9%5%333414%
1551
March1st to 15thDay
18%17%7%9%6%35%34418%
1790
16th to endDay
17%17%6%8%9%4444418%
2211
April1st to 15thDay
20%17%48%6%24445%19%
2156
16th to endDay
20%11%5%6%33345%6%28%
2379
May1st to 15thDay
24%8%35%5%24445%29%
2512
16th to endDay
30%9%46%42344424%
2743
June1st to 15thDay
26%9%47%5%3446%7%21%
2700
16th to endDay
27%8%26%5%2445%5%26%
2741
July1st to 15thDay
25%8%25%4335%5%7%27%
2679
16th to endDay
27%6%25%5%4446%7%24%
2653
August1st to 15thDay
20%7%35%5%2445%7%31%
2520
16th to endDay
28%8%2442345%7%29%
2442
September1st to 15thDay
30%6%34423445%29%
2154
16th to endDay
29%9%26%31345%6%25%
1980
October1st to 15thDay
30%10%36%422335%27%
1815
16th to endDay
34%16%35%42223418%
1728
November1st to 15thDay
28%20%6%7%42343415%
1643
16th to endDay
26%22%8%13%41223212%
1368
December1st to 15thDay
20%21%8%19%10%332324
1260
16th to endDay
20%21%9%13%14%5%21126%
1344
January1st to 15thNight
18%22%8%15%11%6%43224
2580
16th to endNight
16%17%8%14%15%6%6%2136%
2688
February1st to 15thNight
15%16%6%13%16%8%6%3237%
2429
16th to endNight
12%16%9%13%12%34435%12%
1922
March1st to 15thNight
17%16%6%12%9%45%33417%
2147
16th to endNight
17%20%8%9%7%3433317%
2010
April1st to 15thNight
25%16%5%7%7%2343417%
1793
16th to endNight
18%13%5%7%6%34346%26%
1580
May1st to 15thNight
25%10%25%5%23345%30%
1440
16th to endNight
33%9%36%5%24445%21%
1369
June1st to 15thNight
26%11%47%6%35%45%422%
1260
16th to endNight
28%6%36%5%34446%25%
1187
July1st to 15thNight
29%8%245%23446%27%
1279
16th to endNight
30%8%35%5%25%45%5%23%
1515
August1st to 15thNight
23%8%36%5%35%45%6%28%
1440
16th to endNight
27%8%3442445%8%26%
1756
September1st to 15thNight
31%7%25%5%2345%5%26%
1806
16th to endNight
33%8%26%433345%23%
1980
October1st to 15thNight
29%13%35%433335%22%
2144
16th to endNight
34%17%35%5%23235%15%
2496
November1st to 15thNight
29%21%5%6%5%2333413%
2541
16th to endNight
28%23%9%9%41232310%
2916
December1st to 15thNight
22%22%10%15%9%222227%
2700
16th to endNight
20%21%12%13%12%412225%
2880

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
89%15%3
1358
16th to endDay
91%123
1536
February1st to 15thDay
84%35%6%
1432
16th to endDay
77%5%48%4
1551
March1st to 15thDay
72%49%9%5%
1800
16th to endDay
71%6%5%8%7%
2211
April1st to 15thDay
67%6%7%13%3
2156
16th to endDay
55%7%10%16%9%
2379
May1st to 15thDay
56%6%8%19%7%
2512
16th to endDay
63%5%11%14%5%
2747
June1st to 15thDay
61%7%13%14%3
2700
16th to endDay
58%5%16%14%4
2741
July1st to 15thDay
54%5%18%18%3
2522
16th to endDay
57%5%16%17%2
2486
August1st to 15thDay
51%6%19%18%3
2506
16th to endDay
55%6%16%17%3
2442
September1st to 15thDay
58%6%13%17%4
2154
16th to endDay
59%6%14%15%4
1980
October1st to 15thDay
63%410%14%5%
1815
16th to endDay
73%5%7%9%3
1728
November1st to 15thDay
76%47%9%1
1643
16th to endDay
80%36%7%1
1368
December1st to 15thDay
88%15%3
1260
16th to endDay
88%235%
1344
January1st to 15thNight
89%2421
2580
16th to endNight
88%2341
2688
February1st to 15thNight
87%344
2430
16th to endNight
78%46%8%2
1922
March1st to 15thNight
72%5%6%10%4
2160
16th to endNight
72%47%11%3
2010
April1st to 15thNight
71%46%12%4
1793
16th to endNight
59%5%10%15%9%
1580
May1st to 15thNight
55%412%18%7%1
1440
16th to endNight
64%49%17%3
1371
June1st to 15thNight
63%5%10%17%2
1260
16th to endNight
57%5%17%13%5%
1187
July1st to 15thNight
56%5%16%16%4
1208
16th to endNight
60%5%14%16%2
1419
August1st to 15thNight
55%6%17%17%3
1429
16th to endNight
57%5%16%16%3
1756
September1st to 15thNight
60%5%12%19%1
1806
16th to endNight
64%414%14%2
1980
October1st to 15thNight
67%410%12%4
2144
16th to endNight
73%48%10%3
2496
November1st to 15thNight
75%47%9%1
2541
16th to endNight
82%26%6%1
2916
December1st to 15thNight
87%2441
2700
16th to endNight
87%2441
2880

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
23%37%21%12%4
240
16th to endDay
23%31%21%14%7%1
256
February1st to 15thDay
19%31%29%12%6%
236
16th to endDay
29%25%19%13%8%3
212
March1st to 15thDay
24%26%25%12%7%3
240
16th to endDay
27%26%24%13%6%1
279
April1st to 15thDay
33%26%21%12%5%1
273
16th to endDay
23%24%22%16%9%3
450
May1st to 15thDay
27%19%19%19%11%3
468
16th to endDay
33%17%19%18%8%1
519
June1st to 15thDay
32%18%17%17%11%3
495
16th to endDay
30%18%23%15%6%4
495
July1st to 15thDay
30%15%21%21%7%3
475
16th to endDay
29%16%15%24%10%3
514
August1st to 15thDay
24%13%23%20%13%4
493
16th to endDay
32%10%19%21%13%1
457
September1st to 15thDay
36%16%22%16%6%
313
16th to endDay
37%16%26%15%4
269
October1st to 15thDay
33%22%22%12%5%3
270
16th to endDay
41%17%17%14%6%1
288
November1st to 15thDay
33%23%22%15%22
280
16th to endDay
35%24%16%15%5%1
285
December1st to 15thDay
27%32%22%13%3
240
16th to endDay
24%33%21%14%5%1
256
January1st to 15thNight
26%37%20%11%3
750
16th to endNight
18%36%22%15%6%
800
February1st to 15thNight
22%32%23%13%7%
728
16th to endNight
20%30%19%18%7%3
631
March1st to 15thNight
20%31%23%15%7%1
720
16th to endNight
23%28%25%15%6%
612
April1st to 15thNight
31%26%14%19%6%1
539
16th to endNight
25%25%20%17%8%2
540
May1st to 15thNight
26%22%15%20%13%2
540
16th to endNight
32%21%16%19%8%1
561
June1st to 15thNight
30%20%14%22%10%1
540
16th to endNight
27%20%18%22%7%2
467
July1st to 15thNight
31%18%23%15%9%3
510
16th to endNight
29%20%13%23%11%1
565
August1st to 15thNight
25%14%19%20%17%1
539
16th to endNight
31%13%18%20%13%2
573
September1st to 15thNight
35%16%19%19%8%
540
16th to endNight
37%20%21%18%2
538
October1st to 15thNight
38%19%18%15%5%1
677
16th to endNight
42%18%16%16%5%
816
November1st to 15thNight
39%26%16%12%4
805
16th to endNight
37%26%17%13%31
824
December1st to 15thNight
28%33%20%13%3
750
16th to endNight
27%32%17%15%6%1
800
Page generated at 2017-12-01 13:43:33. Version ac04

Copyright 2017 A. Danko


Daniel's Harbour Clear Sky Chart |Charts Home