Port Hardy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Port Hardy clear sky chart from 2005-11-05 to 2017-12-02.

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
32%
14803
5%
47767
4%
14773
33%
14773
9%
39410

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
21%
750
8%
2686
6%
746
25%
746
6%
2311
January16th to endNight
22%
800
5%
2772
5%
800
23%
800
6%
2378
February1st to 15thNight
19%
713
5%
2366
4%
713
21%
713
6%
2040
February16th to endNight
33%
632
9%
2014
8%
632
35%
632
12%
1571
March1st to 15thNight
20%
720
3%
2082
2%
720
21%
720
7%
1808
March16th to endNight
25%
767
4%
2112
3%
767
26%
767
7%
1838
April1st to 15thNight
30%
562
2%
1699
2%
562
30%
562
8%
1441
April16th to endNight
29%
540
6%
1620
5%
540
30%
540
9%
1352
May1st to 15thNight
43%
419
4%
1437
5%
419
44%
419
11%
1117
May16th to endNight
39%
375
2%
1309
2%
374
40%
374
9%
1067
June1st to 15thNight
48%
360
0%
1260
0%
360
48%
360
12%
950
June16th to endNight
37%
360
0%
1260
0%
360
37%
360
11%
1001
July1st to 15thNight
57%
340
2%
1190
1%
340
57%
340
16%
858
July16th to endNight
57%
379
3%
1242
2%
357
60%
357
17%
890
August1st to 15thNight
61%
538
6%
1519
5%
535
61%
535
17%
1128
August16th to endNight
44%
573
5%
1719
4%
573
45%
573
11%
1367
September1st to 15thNight
53%
643
9%
1801
6%
643
54%
643
19%
1325
September16th to endNight
36%
716
8%
1980
6%
716
37%
716
11%
1657
October1st to 15thNight
35%
720
5%
2121
4%
720
36%
720
13%
1698
October16th to endNight
26%
768
4%
2479
4%
768
27%
768
6%
2167
November1st to 15thNight
19%
760
4%
2639
3%
760
21%
760
5%
2343
November16th to endNight
23%
808
4%
2850
5%
808
24%
808
7%
2399
December1st to 15thNight
23%
760
5%
2730
4%
760
26%
760
7%
2264
December16th to endNight
21%
800
5%
2880
3%
800
23%
800
7%
2440

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
30%12%48%6%3434415%
48718
Night
30%11%47%6%34445%18%
47912
TransparencyDay
71%6%11%7%2
48367
Night
68%6%12%9%3
47767
SeeingDay
32%5%18%24%14%3
6905
Night
35%5%14%21%16%5%
14809

By Month

Percentage Cloud Cover NW (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
41%15%46%5%1322313%
1253
16th to endDay
37%12%5%6%6%4433312%
1449
February1st to 15thDay
37%14%6%7%5%3323312%
1497
16th to endDay
29%13%47%5%3333320%
1457
March1st to 15thDay
36%16%5%8%7%333338%
1878
16th to endDay
30%16%6%10%7%3433310%
2112
April1st to 15thDay
32%15%5%9%7%443439%
2247
16th to endDay
32%15%5%9%7%3424312%
2340
May1st to 15thDay
29%11%48%7%35%335%17%
2511
16th to endDay
29%13%5%8%7%35%33414%
2804
June1st to 15thDay
26%14%5%8%6%4445%6%13%
2700
16th to endDay
37%10%48%6%3443312%
2700
July1st to 15thDay
23%10%47%6%3435%5%24%
2700
16th to endDay
22%12%47%6%34446%21%
2840
August1st to 15thDay
18%10%39%7%445%5%6%24%
2432
16th to endDay
24%13%410%7%45%45%5%14%
2483
September1st to 15thDay
22%11%37%6%34447%24%
2155
16th to endDay
30%11%5%8%7%45%44414%
1980
October1st to 15thDay
31%12%6%7%6%3434415%
1839
16th to endDay
38%12%48%6%444338%
1743
November1st to 15thDay
43%11%47%5%3422312%
1549
16th to endDay
36%10%37%5%445%4314%
1438
December1st to 15thDay
29%14%48%7%45%335%14%
1267
16th to endDay
34%14%5%9%6%3334211%
1344
January1st to 15thNight
38%13%47%5%2322215%
2686
16th to endNight
38%13%37%6%3332413%
2772
February1st to 15thNight
38%11%5%8%6%2333314%
2354
16th to endNight
25%15%46%42433423%
2014
March1st to 15thNight
30%15%47%6%3444413%
2082
16th to endNight
30%14%5%8%7%3433313%
2108
April1st to 15thNight
27%13%5%8%7%45%346%14%
1699
16th to endNight
27%12%48%7%4434416%
1620
May1st to 15thNight
26%8%35%6%25%5%46%23%
1436
16th to endNight
21%10%48%7%46%45%420%
1309
June1st to 15thNight
20%8%36%6%36%5%5%8%25%
1260
16th to endNight
26%10%6%6%6%3445%7%20%
1260
July1st to 15thNight
18%6%26%6%45%346%34%
1260
16th to endNight
13%8%36%5%35%5%7%8%32%
1326
August1st to 15thNight
9%7%36%6%47%7%6%9%30%
1527
16th to endNight
18%9%49%7%35%5%5%6%23%
1719
September1st to 15thNight
16%7%25%6%345%5%9%33%
1801
16th to endNight
30%10%26%6%35%5%45%19%
1980
October1st to 15thNight
33%8%35%435%44422%
2121
16th to endNight
37%10%47%6%3433412%
2479
November1st to 15thNight
40%11%48%6%3432311%
2639
16th to endNight
35%11%47%5%3344415%
2850
December1st to 15thNight
33%13%46%6%3433317%
2730
16th to endNight
35%13%46%5%3334414%
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
78%35%6%41
1253
16th to endDay
76%38%7%22
1449
February1st to 15thDay
77%37%5%41
1497
16th to endDay
67%410%11%5%
1457
March1st to 15thDay
81%38%41
1878
16th to endDay
78%5%10%41
2112
April1st to 15thDay
78%48%6%1
2247
16th to endDay
76%39%6%2
2340
May1st to 15thDay
67%6%13%9%2
2511
16th to endDay
72%6%11%8%1
2808
June1st to 15thDay
70%7%14%41
2700
16th to endDay
74%7%11%6%
2700
July1st to 15thDay
60%10%12%12%3
2541
16th to endDay
60%9%18%10%1
2661
August1st to 15thDay
58%11%14%10%4
2415
16th to endDay
68%10%12%7%1
2483
September1st to 15thDay
58%8%15%12%4
2155
16th to endDay
69%8%10%7%3
1980
October1st to 15thDay
72%5%9%8%3
1839
16th to endDay
78%6%6%5%2
1743
November1st to 15thDay
78%5%7%5%2
1549
16th to endDay
73%48%7%5%
1438
December1st to 15thDay
72%5%8%8%5%
1267
16th to endDay
77%37%5%4
1344
January1st to 15thNight
76%46%7%5%
2686
16th to endNight
75%37%7%22
2772
February1st to 15thNight
75%46%7%5%
2366
16th to endNight
64%312%14%4
2014
March1st to 15thNight
75%410%8%1
2082
16th to endNight
74%5%12%6%1
2112
April1st to 15thNight
71%5%12%7%2
1699
16th to endNight
70%5%10%10%21
1620
May1st to 15thNight
60%8%16%11%3
1437
16th to endNight
65%8%17%7%1
1309
June1st to 15thNight
57%8%21%10%2
1260
16th to endNight
62%7%18%9%1
1260
July1st to 15thNight
49%10%18%15%5%
1190
16th to endNight
44%14%26%11%3
1242
August1st to 15thNight
48%12%21%14%2
1519
16th to endNight
59%11%16%11%
1719
September1st to 15thNight
50%8%18%17%5%
1801
16th to endNight
66%7%10%11%3
1980
October1st to 15thNight
64%5%12%13%4
2121
16th to endNight
74%6%10%5%2
2479
November1st to 15thNight
79%46%5%21
2639
16th to endNight
73%48%8%41
2850
December1st to 15thNight
72%410%7%5%
2730
16th to endNight
73%48%7%41
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
30%10%13%26%13%6%
60
16th to endDay
46%8%19%14%8%2
169
February1st to 15thDay
47%418%20%7%1
236
16th to endDay
33%9%22%15%14%4
211
March1st to 15thDay
44%10%24%10%9%
254
16th to endDay
42%8%20%16%8%3
288
April1st to 15thDay
39%8%22%18%8%2
269
16th to endDay
37%9%21%22%7%1
270
May1st to 15thDay
34%418%27%10%4
348
16th to endDay
30%6%20%27%13%2
518
June1st to 15thDay
32%5%18%25%15%3
495
16th to endDay
34%316%27%14%2
495
July1st to 15thDay
21%319%28%24%2
475
16th to endDay
20%216%33%21%4
515
August1st to 15thDay
18%113%30%27%8%
406
16th to endDay
26%318%29%18%2
332
September1st to 15thDay
29%315%22%19%9%
315
16th to endDay
35%5%13%24%15%5%
315
October1st to 15thDay
33%6%22%19%10%6%
315
16th to endDay
44%420%18%10%2
292
November1st to 15thDay
39%9%24%16%9%1
111
16th to endDay
36%13%20%10%8%11%
90
December1st to 15thDay
40%316%19%14%6%
62
16th to endDay
35%423%28%7%
64
January1st to 15thNight
42%7%18%19%9%2
750
16th to endNight
45%5%15%16%13%3
800
February1st to 15thNight
44%7%18%18%9%1
717
16th to endNight
33%7%16%21%16%5%
632
March1st to 15thNight
39%8%22%18%9%2
720
16th to endNight
36%8%15%20%13%4
768
April1st to 15thNight
33%6%14%24%13%6%
562
16th to endNight
33%417%27%14%2
540
May1st to 15thNight
30%49%24%26%5%
420
16th to endNight
25%6%9%30%21%6%
375
June1st to 15thNight
22%5%11%25%26%8%
360
16th to endNight
26%412%27%23%5%
360
July1st to 15thNight
20%37%27%31%9%
340
16th to endNight
15%37%26%34%13%
379
August1st to 15thNight
14%26%21%34%19%
538
16th to endNight
24%28%27%30%6%
573
September1st to 15thNight
18%310%22%28%16%
643
16th to endNight
34%210%22%20%8%
716
October1st to 15thNight
37%312%22%16%7%
720
16th to endNight
43%315%19%13%5%
768
November1st to 15thNight
46%6%17%20%7%1
760
16th to endNight
41%7%17%18%10%4
808
December1st to 15thNight
41%6%19%18%11%2
760
16th to endNight
42%7%22%18%7%1
800
Page generated at 2017-12-03 08:16:45. Version ac04

Copyright 2017 A. Danko


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