Pinawa
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pinawa clear sky chart from 2005-11-06 to 2024-01-12.

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
35%
25109
11%
74714
7%
25058
39%
25058
19%
53807

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 10thNight
28%
950
7%
2837
5%
946
31%
946
11%
2285
January11th to 20thNight
27%
906
7%
2716
4%
906
30%
906
11%
2156
January21st to endNight
26%
990
9%
2840
4%
990
30%
990
12%
2306
February1st to 10thNight
35%
900
12%
2367
7%
900
37%
900
19%
1781
February11th to 20thNight
39%
877
15%
2274
8%
875
43%
875
25%
1610
February21st to endNight
33%
740
16%
1924
7%
740
39%
740
19%
1441
March1st to 10thNight
36%
642
14%
2082
11%
642
40%
642
17%
1506
March11th to 20thNight
34%
540
18%
1980
11%
540
46%
540
21%
1249
March21st to endNight
39%
594
17%
2178
17%
594
45%
594
17%
1448
April1st to 10thNight
41%
540
16%
1774
17%
540
48%
540
23%
1143
April11th to 20thNight
39%
533
18%
1599
13%
533
47%
533
23%
1091
April21st to endNight
38%
540
14%
1620
9%
540
43%
540
22%
1099
May1st to 10thNight
33%
540
14%
1481
5%
540
37%
540
24%
1023
May11th to 20thNight
41%
531
13%
1344
6%
531
44%
531
31%
897
May21st to endNight
39%
584
10%
1358
5%
582
42%
582
30%
961
June1st to 10thNight
44%
540
4%
1260
2%
540
46%
540
29%
897
June11th to 20thNight
40%
540
3%
1260
3%
540
42%
540
30%
891
June21st to endNight
52%
540
4%
1260
4%
540
53%
540
31%
868
July1st to 10thNight
59%
525
8%
1225
6%
525
62%
525
48%
729
July11th to 20thNight
53%
522
8%
1218
4%
522
54%
522
40%
792
July21st to endNight
59%
591
16%
1302
8%
558
61%
558
46%
800
August1st to 10thNight
59%
537
17%
1500
9%
534
61%
534
39%
868
August11th to 20thNight
58%
534
17%
1600
10%
534
62%
534
33%
941
August21st to endNight
50%
594
20%
1782
18%
594
56%
594
32%
1086
September1st to 10thNight
48%
540
16%
1742
17%
540
52%
540
31%
1028
September11th to 20thNight
40%
540
15%
1934
14%
540
46%
540
21%
1221
September21st to endNight
35%
540
20%
1980
15%
540
45%
540
21%
1256
October1st to 10thNight
33%
710
12%
2150
7%
710
37%
710
18%
1512
October11th to 20thNight
30%
720
15%
2160
9%
720
35%
720
17%
1594
October21st to endNight
26%
972
10%
2592
4%
972
30%
972
14%
2027
November1st to 10thNight
22%
925
9%
2591
4%
925
27%
925
13%
2048
November11th to 20thNight
21%
950
8%
2660
4%
950
25%
950
11%
2186
November21st to endNight
16%
950
5%
2724
1%
950
20%
950
9%
2299
December1st to 10thNight
26%
950
4%
2850
2%
950
29%
950
10%
2351
December11th to 20thNight
19%
949
7%
3452
3%
949
23%
949
8%
2666
December21st to endNight
26%
1033
5%
5098
5%
1026
30%
1026
6%
3751

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
13%9%47%7%45%5%6%7%33%
74668
Night
11%10%5%8%7%45%5%6%7%32%
75067
TransparencyDay
49%7%14%21%8%1
74349
Night
51%7%14%20%8%1
74905
SeeingDay
15%10%31%28%14%3
15062
Night
16%7%31%32%12%1
25124

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 10thDay
8%13%7%12%9%6%9%7%6%6%18%
1329
11th to 20thDay
8%14%7%12%9%48%7%8%6%16%
1267
21st to endDay
10%16%7%14%11%5%8%7%9%5%9%
1515
February1st to 10thDay
7%11%6%9%8%6%9%8%8%9%19%
1592
11th to 20thDay
8%10%5%9%8%5%9%7%8%7%25%
1574
21st to endDay
6%11%6%12%9%5%7%6%6%6%25%
1344
March1st to 10thDay
11%12%6%9%7%46%7%5%6%27%
1882
11th to 20thDay
9%9%6%9%8%45%6%5%7%32%
1978
21st to endDay
10%12%6%7%7%35%46%8%33%
2178
April1st to 10thDay
12%11%47%6%335%5%7%36%
2184
11th to 20thDay
13%8%46%6%35%45%7%37%
2312
21st to endDay
15%10%46%5%36%5%6%7%34%
2340
May1st to 10thDay
15%9%36%5%345%47%38%
2478
11th to 20thDay
18%7%36%5%35%45%8%36%
2548
21st to endDay
19%7%36%6%3445%7%37%
2918
June1st to 10thDay
15%6%35%7%46%45%8%35%
2700
11th to 20thDay
17%7%35%6%36%5%6%8%34%
2700
21st to endDay
14%6%36%6%46%6%6%9%33%
2700
July1st to 10thDay
9%5%24435%6%6%9%47%
2700
11th to 20thDay
12%5%25%5%35%6%6%9%43%
2700
21st to endDay
10%5%345%345%6%8%46%
2939
August1st to 10thDay
9%6%36%6%35%5%5%8%43%
2429
11th to 20thDay
12%5%25%5%35%5%6%9%43%
2301
21st to endDay
15%6%345%345%5%7%44%
2574
September1st to 10thDay
13%5%246%4446%7%44%
2217
11th to 20thDay
15%6%37%6%35%6%6%9%34%
2024
21st to endDay
18%7%36%5%3445%7%38%
1972
October1st to 10thDay
19%13%37%6%35%446%29%
1800
11th to 20thDay
16%14%5%7%5%3445%8%30%
1800
21st to endDay
18%16%5%10%8%345%5%5%22%
1761
November1st to 10thDay
17%16%7%10%5%45%445%23%
1487
11th to 20thDay
12%15%7%12%10%35%36%6%21%
1520
21st to endDay
12%15%6%12%12%35%45%7%19%
1454
December1st to 10thDay
9%13%7%17%11%6%7%6%5%5%13%
1330
11th to 20thDay
10%13%7%12%9%447%6%7%19%
1679
21st to endDay
11%12%5%12%9%5%6%7%7%7%20%
2442
January1st to 10thNight
7%14%7%12%9%6%7%7%6%6%18%
2837
11th to 20thNight
9%14%6%12%10%5%7%7%7%7%17%
2716
21st to endNight
8%15%7%11%10%5%8%7%8%7%15%
2840
February1st to 10thNight
7%12%5%9%8%5%7%7%7%8%26%
2367
11th to 20thNight
6%11%5%7%6%46%7%8%8%31%
2273
21st to endNight
7%10%5%11%8%5%6%6%5%6%30%
1924
March1st to 10thNight
9%12%6%9%7%46%5%6%7%31%
2082
11th to 20thNight
9%8%47%7%34447%42%
1980
21st to endNight
12%12%47%6%3445%6%36%
2178
April1st to 10thNight
12%9%35%5%45%5%6%6%40%
1774
11th to 20thNight
14%10%47%5%345%5%7%37%
1599
21st to endNight
12%9%48%6%46%5%5%7%36%
1620
May1st to 10thNight
16%9%35%5%346%5%6%37%
1481
11th to 20thNight
16%8%25%425%46%7%43%
1344
21st to endNight
18%6%25%42447%7%41%
1358
June1st to 10thNight
13%7%36%5%35%5%6%9%39%
1260
11th to 20thNight
14%6%37%5%2446%8%41%
1260
21st to endNight
12%6%246%45%5%6%8%43%
1260
July1st to 10thNight
7%22333446%8%58%
1260
11th to 20thNight
7%4245%25%6%7%9%49%
1260
21st to endNight
7%42342447%8%55%
1379
August1st to 10thNight
7%325%5%2446%8%53%
1507
11th to 20thNight
10%325%425%5%6%8%50%
1600
21st to endNight
13%6%15%42336%8%48%
1782
September1st to 10thNight
12%4245%2445%7%49%
1742
11th to 20thNight
16%6%35%5%345%5%7%42%
1934
21st to endNight
18%8%245%2445%8%40%
1980
October1st to 10thNight
17%9%36%6%35%447%35%
2150
11th to 20thNight
17%13%47%6%35%5%5%7%29%
2160
21st to endNight
19%14%48%6%345%5%5%27%
2592
November1st to 10thNight
15%15%6%10%7%45%5%45%25%
2591
11th to 20thNight
12%15%7%14%10%44435%22%
2660
21st to endNight
13%15%7%14%10%5%5%5%45%18%
2724
December1st to 10thNight
7%12%6%14%13%6%7%6%5%7%17%
2850
11th to 20thNight
9%14%7%13%9%46%7%6%6%20%
3518
21st to endNight
9%11%7%12%10%5%6%6%6%5%22%
5225

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 10thDay
64%6%11%14%4
1329
11th to 20thDay
64%412%15%5%
1267
21st to endDay
71%5%6%12%7%
1515
February1st to 10thDay
58%7%12%14%8%1
1592
11th to 20thDay
54%5%13%19%8%
1583
21st to endDay
56%7%12%16%9%
1344
March1st to 10thDay
57%5%12%17%7%
1882
11th to 20thDay
50%8%14%20%8%1
1980
21st to endDay
50%7%14%21%7%1
2178
April1st to 10thDay
48%6%12%23%11%1
2184
11th to 20thDay
47%5%11%22%14%2
2312
21st to endDay
47%6%14%22%9%1
2340
May1st to 10thDay
45%7%10%23%13%2
2478
11th to 20thDay
46%6%11%22%13%2
2552
21st to endDay
47%7%11%20%14%1
2918
June1st to 10thDay
47%7%13%22%11%1
2700
11th to 20thDay
46%9%15%19%11%1
2700
21st to endDay
45%9%18%21%7%
2700
July1st to 10thDay
31%7%18%31%12%1
2626
11th to 20thDay
35%8%17%30%10%
2619
21st to endDay
36%8%18%28%10%
2776
August1st to 10thDay
38%8%17%29%8%
2412
11th to 20thDay
36%9%21%29%5%
2301
21st to endDay
39%7%16%30%7%
2574
September1st to 10thDay
38%7%17%29%9%1
2217
11th to 20thDay
45%9%19%22%5%
2024
21st to endDay
46%5%15%30%5%
1972
October1st to 10thDay
56%7%14%18%5%
1800
11th to 20thDay
53%7%14%20%5%
1800
21st to endDay
64%7%15%12%2
1761
November1st to 10thDay
64%7%12%12%41
1487
11th to 20thDay
64%8%12%12%3
1520
21st to endDay
66%6%16%10%2
1454
December1st to 10thDay
71%7%12%8%3
1330
11th to 20thDay
60%6%18%12%4
1680
21st to endDay
57%9%12%18%4
2442
January1st to 10thNight
65%6%10%15%4
2837
11th to 20thNight
63%7%11%15%4
2716
21st to endNight
65%6%9%15%5%
2840
February1st to 10thNight
54%6%14%17%9%1
2367
11th to 20thNight
46%7%18%21%9%
2274
21st to endNight
53%6%12%19%10%
1924
March1st to 10thNight
52%7%12%18%11%1
2082
11th to 20thNight
43%6%14%24%12%1
1980
21st to endNight
48%6%13%20%12%1
2178
April1st to 10thNight
44%5%11%22%15%3
1774
11th to 20thNight
47%5%9%20%16%3
1599
21st to endNight
47%5%10%24%13%1
1620
May1st to 10thNight
46%6%11%24%13%1
1481
11th to 20thNight
41%5%14%26%12%3
1344
21st to endNight
41%7%12%21%16%3
1358
June1st to 10thNight
40%9%18%20%10%1
1260
11th to 20thNight
41%7%14%21%15%2
1260
21st to endNight
38%8%18%27%7%1
1260
July1st to 10thNight
23%7%16%38%15%1
1225
11th to 20thNight
28%11%20%28%12%1
1218
21st to endNight
26%7%18%36%12%1
1302
August1st to 10thNight
27%7%19%35%11%1
1500
11th to 20thNight
30%8%21%31%10%
1600
21st to endNight
35%6%16%33%10%1
1782
September1st to 10thNight
34%7%16%32%12%
1742
11th to 20thNight
41%8%17%25%9%1
1934
21st to endNight
43%7%14%29%7%
1980
October1st to 10thNight
49%7%16%20%8%
2150
11th to 20thNight
54%7%14%21%4
2160
21st to endNight
58%7%15%16%3
2592
November1st to 10thNight
62%6%15%13%41
2591
11th to 20thNight
66%6%13%11%4
2660
21st to endNight
69%6%12%9%3
2724
December1st to 10thNight
68%6%15%9%2
2850
11th to 20thNight
61%8%14%13%5%
3516
21st to endNight
59%7%12%16%6%
5225

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 10thDay
10%8%36%29%16%2
270
11th to 20thDay
11%10%27%34%16%1
243
21st to endDay
17%6%30%30%14%2
264
February1st to 10thDay
13%12%30%35%8%3
240
11th to 20thDay
13%16%28%26%13%3
240
21st to endDay
8%9%38%31%12%1
198
March1st to 10thDay
10%9%33%33%14%2
240
11th to 20thDay
9%14%25%35%14%3
240
21st to endDay
14%9%30%30%15%2
264
April1st to 10thDay
17%9%32%30%9%2
444
11th to 20thDay
18%12%29%28%11%2
590
21st to endDay
17%11%34%27%11%2
600
May1st to 10thDay
16%15%32%26%11%2
603
11th to 20thDay
21%9%26%27%15%2
625
21st to endDay
19%10%25%26%17%2
679
June1st to 10thDay
15%11%30%24%15%4
630
11th to 20thDay
16%11%34%25%11%3
630
21st to endDay
14%6%27%29%18%6%
630
July1st to 10thDay
10%9%30%28%17%6%
621
11th to 20thDay
12%10%29%27%18%4
618
21st to endDay
9%6%28%29%20%8%
684
August1st to 10thDay
10%8%30%29%17%6%
626
11th to 20thDay
10%6%27%32%16%9%
615
21st to endDay
15%8%27%27%19%4
693
September1st to 10thDay
13%9%30%33%13%2
507
11th to 20thDay
16%9%36%27%10%2
314
21st to endDay
21%9%36%27%7%1
270
October1st to 10thDay
24%9%27%29%9%3
270
11th to 20thDay
19%11%31%31%7%1
270
21st to endDay
30%11%29%23%7%1
297
November1st to 10thDay
23%9%32%27%8%1
270
11th to 20thDay
17%8%44%23%7%
270
21st to endDay
18%13%40%23%6%
270
December1st to 10thDay
12%7%36%29%14%3
270
11th to 20thDay
15%7%40%30%8%
270
21st to endDay
13%7%31%32%12%5%
297
January1st to 10thNight
12%9%33%31%13%2
950
11th to 20thNight
15%7%35%33%9%1
906
21st to endNight
15%6%35%32%10%1
990
February1st to 10thNight
12%6%33%36%12%1
900
11th to 20thNight
11%6%33%34%14%2
879
21st to endNight
10%7%36%31%13%2
740
March1st to 10thNight
12%7%33%31%15%1
642
11th to 20thNight
13%7%39%28%11%2
540
21st to endNight
18%9%26%29%15%3
594
April1st to 10thNight
16%7%28%38%9%2
540
11th to 20thNight
17%7%28%35%13%
533
21st to endNight
14%8%31%37%11%
540
May1st to 10thNight
18%7%33%33%9%1
540
11th to 20thNight
19%7%29%30%14%1
531
21st to endNight
20%7%30%29%13%1
584
June1st to 10thNight
16%5%28%33%18%1
540
11th to 20thNight
14%7%31%32%15%
540
21st to endNight
13%5%21%39%19%2
540
July1st to 10thNight
6%5%26%41%21%2
525
11th to 20thNight
8%6%26%38%20%2
522
21st to endNight
9%324%39%23%3
591
August1st to 10thNight
9%424%41%22%2
537
11th to 20thNight
10%5%23%38%21%4
534
21st to endNight
16%5%22%37%19%2
594
September1st to 10thNight
15%430%34%15%2
540
11th to 20thNight
21%5%28%33%12%
540
21st to endNight
19%8%31%30%11%1
540
October1st to 10thNight
23%8%31%30%7%
710
11th to 20thNight
22%8%31%29%8%1
720
21st to endNight
26%10%29%27%8%1
972
November1st to 10thNight
21%10%35%24%9%1
925
11th to 20thNight
19%10%35%26%8%2
950
21st to endNight
20%12%39%22%6%1
950
December1st to 10thNight
13%8%34%33%11%2
950
11th to 20thNight
17%10%36%29%7%1
950
21st to endNight
16%9%28%31%14%1
1045
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