Prince George
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prince George clear sky chart from 2005-11-06 to 2024-03-28.

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
39%
23537
8%
81710
6%
23434
42%
23434
13%
61539

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
26%
937
9%
4864
3%
922
29%
922
4%
3843
January11th to 20thNight
25%
835
15%
4622
6%
820
29%
820
5%
3271
January21st to endNight
24%
928
5%
5204
6%
902
28%
902
4%
4454
February1st to 10thNight
30%
774
8%
2644
6%
774
34%
774
10%
2088
February11th to 20thNight
35%
741
9%
2404
7%
740
39%
740
12%
1844
February21st to endNight
38%
628
13%
2041
10%
628
43%
628
15%
1497
March1st to 10thNight
39%
760
12%
2300
10%
760
42%
760
14%
1751
March11th to 20thNight
38%
760
13%
2089
8%
760
41%
760
17%
1564
March21st to endNight
46%
820
10%
2169
6%
820
47%
820
18%
1664
April1st to 10thNight
43%
720
8%
1800
5%
720
44%
720
19%
1389
April11th to 20thNight
44%
543
10%
1611
7%
543
46%
543
17%
1202
April21st to endNight
41%
370
10%
1450
10%
370
47%
370
14%
1005
May1st to 10thNight
41%
360
5%
1440
6%
360
43%
360
12%
1040
May11th to 20thNight
53%
354
4%
1307
2%
354
53%
354
16%
900
May21st to endNight
50%
388
0%
1222
0%
388
50%
388
19%
861
June1st to 10thNight
46%
360
0%
1080
0%
360
46%
360
17%
795
June11th to 20thNight
43%
360
0%
1080
0%
360
43%
360
15%
824
June21st to endNight
53%
360
0%
1080
0%
360
53%
360
19%
776
July1st to 10thNight
57%
350
0%
1050
0%
350
57%
350
22%
723
July11th to 20thNight
58%
348
0%
1194
0%
348
58%
348
20%
789
July21st to endNight
63%
394
4%
1302
2%
372
65%
372
25%
812
August1st to 10thNight
69%
358
8%
1361
11%
356
71%
356
27%
749
August11th to 20thNight
66%
391
16%
1459
20%
391
71%
391
27%
842
August21st to endNight
51%
594
10%
1782
9%
594
53%
594
17%
1313
September1st to 10thNight
54%
718
11%
1798
6%
718
55%
718
26%
1269
September11th to 20thNight
59%
720
19%
1800
11%
720
60%
720
28%
1244
September21st to endNight
41%
720
13%
2060
7%
720
44%
720
18%
1524
October1st to 10thNight
45%
720
10%
2160
6%
720
49%
720
18%
1556
October11th to 20thNight
37%
720
10%
2168
8%
720
42%
720
15%
1633
October21st to endNight
33%
792
9%
2712
6%
792
39%
792
12%
2030
November1st to 10thNight
32%
740
9%
2590
7%
740
35%
740
9%
2018
November11th to 20thNight
27%
760
9%
2660
6%
760
33%
760
9%
2118
November21st to endNight
27%
999
7%
2964
3%
999
30%
999
10%
2436
December1st to 10thNight
35%
1040
9%
3040
5%
1040
38%
1040
12%
2441
December11th to 20thNight
30%
1040
5%
3746
3%
1039
32%
1039
7%
3193
December21st to endNight
28%
1135
5%
5457
4%
1114
31%
1114
6%
4081

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
11%11%48%7%46%6%6%7%30%
77838
Night
13%13%5%8%7%46%5%6%7%27%
82108
TransparencyDay
50%11%16%17%6%
77531
Night
55%10%13%15%6%1
81995
SeeingDay
16%10%23%26%19%6%
15454
Night
20%8%20%30%18%3
23591

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
10%18%7%13%10%5%7%6%45%16%
2063
11th to 20thDay
13%16%6%9%5%345%5%6%29%
2199
21st to endDay
12%20%7%11%8%47%6%5%5%14%
2442
February1st to 10thDay
15%16%5%8%7%3446%7%24%
1534
11th to 20thDay
12%14%5%9%8%46%6%5%7%24%
1665
21st to endDay
6%16%5%9%9%46%46%6%29%
1413
March1st to 10thDay
9%14%48%6%45%6%6%8%29%
1878
11th to 20thDay
8%13%5%7%8%46%6%7%8%28%
2090
21st to endDay
8%13%5%9%7%46%6%6%7%30%
2341
April1st to 10thDay
7%11%6%11%10%46%6%7%7%26%
2160
11th to 20thDay
11%11%5%9%8%5%6%6%6%6%26%
2296
21st to endDay
13%11%5%8%7%5%5%46%7%30%
2509
May1st to 10thDay
12%11%5%9%7%45%46%7%29%
2520
11th to 20thDay
10%8%47%7%45%7%7%8%32%
2584
21st to endDay
10%8%47%8%5%7%6%7%8%31%
3050
June1st to 10thDay
11%7%48%8%47%7%7%8%29%
2880
11th to 20thDay
14%7%38%8%6%7%6%6%8%27%
2880
21st to endDay
11%7%37%7%46%7%7%8%34%
2880
July1st to 10thDay
12%6%36%6%46%7%6%8%37%
2880
11th to 20thDay
11%7%36%6%35%6%7%9%36%
2722
21st to endDay
9%5%25%5%36%7%6%9%43%
2938
August1st to 10thDay
6%5%245%45%6%7%9%46%
2571
11th to 20thDay
8%5%26%6%35%6%6%9%45%
2439
21st to endDay
11%7%38%7%5%6%7%7%8%31%
2574
September1st to 10thDay
11%6%36%7%36%5%6%8%39%
2162
11th to 20thDay
11%6%37%6%45%6%7%7%38%
2160
21st to endDay
16%8%47%8%46%5%6%7%29%
1899
October1st to 10thDay
15%10%38%7%45%5%6%8%30%
1800
11th to 20thDay
15%11%37%6%5%6%5%5%8%28%
1792
21st to endDay
17%11%47%6%345%5%7%29%
1643
November1st to 10thDay
20%13%5%9%7%35%5%5%424%
1488
11th to 20thDay
12%16%6%11%10%5%6%6%5%6%17%
1508
21st to endDay
14%18%6%9%8%46%9%5%417%
1206
December1st to 10thDay
14%14%5%12%10%46%6%5%5%20%
1140
11th to 20thDay
19%19%6%9%8%45%5%46%16%
1442
21st to endDay
8%16%5%9%9%5%7%6%6%7%22%
2090
January1st to 10thNight
12%16%6%12%9%5%7%7%5%5%16%
4910
11th to 20thNight
13%15%5%9%7%46%446%29%
4699
21st to endNight
20%22%6%10%8%45%44413%
5214
February1st to 10thNight
15%18%5%8%8%445%5%5%23%
2644
11th to 20thNight
12%14%6%9%8%45%5%5%7%25%
2402
21st to endNight
9%14%6%10%7%35%5%5%7%30%
2041
March1st to 10thNight
8%14%5%10%7%47%5%5%7%27%
2300
11th to 20thNight
8%13%5%8%8%5%6%5%6%7%30%
2089
21st to endNight
8%12%48%8%46%7%7%7%28%
2169
April1st to 10thNight
10%12%5%8%7%46%6%6%8%28%
1800
11th to 20thNight
10%11%47%7%49%6%7%8%26%
1611
21st to endNight
12%9%46%6%47%5%6%6%33%
1450
May1st to 10thNight
13%11%48%7%46%5%6%7%29%
1440
11th to 20thNight
10%8%38%8%48%6%7%7%31%
1307
21st to endNight
13%7%37%7%45%7%7%8%32%
1222
June1st to 10thNight
14%8%46%6%5%8%5%8%7%28%
1080
11th to 20thNight
15%9%48%7%47%5%8%7%27%
1080
21st to endNight
10%6%38%7%5%7%6%8%9%30%
1080
July1st to 10thNight
9%7%37%8%46%6%8%9%34%
1080
11th to 20thNight
12%6%35%6%35%6%6%8%39%
1234
21st to endNight
12%435%435%5%7%8%44%
1379
August1st to 10thNight
7%4245%245%6%9%50%
1368
11th to 20thNight
7%425%5%35%6%6%8%50%
1459
21st to endNight
14%8%37%7%45%6%6%7%32%
1782
September1st to 10thNight
12%7%36%6%45%5%6%8%38%
1798
11th to 20thNight
10%8%35%5%45%5%5%8%43%
1800
21st to endNight
16%10%46%6%35%5%6%7%32%
2060
October1st to 10thNight
14%9%37%6%45%46%8%32%
2160
11th to 20thNight
17%11%47%6%35%6%6%6%28%
2168
21st to endNight
15%12%47%5%46%6%5%7%28%
2712
November1st to 10thNight
18%14%5%6%6%46%6%6%6%23%
2590
11th to 20thNight
12%15%5%10%9%5%6%5%6%7%21%
2660
21st to endNight
12%19%6%10%7%46%5%6%7%19%
2964
December1st to 10thNight
12%14%5%9%8%5%7%6%5%5%24%
3040
11th to 20thNight
18%18%6%9%7%45%5%5%6%17%
3750
21st to endNight
8%14%6%10%9%6%7%6%6%6%22%
5566

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
62%14%9%12%2
2063
11th to 20thDay
55%8%13%10%11%4
2220
21st to endDay
67%12%11%7%3
2442
February1st to 10thDay
59%9%12%10%10%
1534
11th to 20thDay
58%10%14%14%5%
1674
21st to endDay
54%9%13%14%8%2
1413
March1st to 10thDay
51%9%13%17%9%1
1878
11th to 20thDay
50%12%15%17%6%
2090
21st to endDay
53%8%17%17%5%
2341
April1st to 10thDay
54%11%12%16%5%1
2160
11th to 20thDay
57%8%11%19%6%
2296
21st to endDay
53%8%14%17%7%
2509
May1st to 10thDay
53%9%15%17%5%
2520
11th to 20thDay
47%10%15%19%8%1
2587
21st to endDay
49%10%15%19%6%1
3051
June1st to 10thDay
49%12%13%18%8%
2880
11th to 20thDay
51%11%15%18%4
2880
21st to endDay
43%12%17%21%6%
2880
July1st to 10thDay
42%11%17%22%7%1
2801
11th to 20thDay
43%10%22%21%3
2639
21st to endDay
33%12%24%25%6%
2775
August1st to 10thDay
32%12%25%25%6%
2553
11th to 20thDay
34%11%23%25%6%
2439
21st to endDay
48%11%19%18%4
2574
September1st to 10thDay
41%11%24%20%4
2162
11th to 20thDay
41%11%19%24%6%
2160
21st to endDay
52%11%15%17%41
1899
October1st to 10thDay
49%10%22%15%4
1800
11th to 20thDay
53%11%16%19%1
1792
21st to endDay
53%10%17%16%4
1643
November1st to 10thDay
60%9%12%13%5%
1488
11th to 20thDay
64%13%10%10%4
1508
21st to endDay
67%12%10%9%2
1206
December1st to 10thDay
63%11%11%12%3
1140
11th to 20thDay
68%11%8%8%4
1444
21st to endDay
56%10%15%13%6%
2090
January1st to 10thNight
61%13%12%12%2
4910
11th to 20thNight
57%7%10%7%12%6%
4740
21st to endNight
71%10%9%7%3
5214
February1st to 10thNight
63%7%12%10%8%1
2644
11th to 20thNight
58%9%14%14%6%
2404
21st to endNight
52%9%13%16%8%1
2041
March1st to 10thNight
53%11%11%14%9%1
2300
11th to 20thNight
51%10%12%19%7%1
2090
21st to endNight
53%10%14%18%5%
2169
April1st to 10thNight
52%9%13%19%7%
1800
11th to 20thNight
53%8%13%19%6%
1611
21st to endNight
51%9%11%19%11%
1450
May1st to 10thNight
52%11%13%17%7%
1440
11th to 20thNight
47%10%13%20%9%1
1307
21st to endNight
47%9%13%23%7%
1222
June1st to 10thNight
50%10%12%18%9%
1080
11th to 20thNight
53%12%12%18%6%
1080
21st to endNight
47%11%19%19%4
1080
July1st to 10thNight
44%10%17%20%9%1
1050
11th to 20thNight
42%10%18%24%5%1
1194
21st to endNight
35%12%21%24%8%
1302
August1st to 10thNight
30%9%23%28%9%
1361
11th to 20thNight
31%10%19%31%8%1
1459
21st to endNight
49%11%17%18%41
1782
September1st to 10thNight
42%10%20%22%6%1
1798
11th to 20thNight
39%10%14%28%9%
1800
21st to endNight
50%10%14%18%8%
2060
October1st to 10thNight
49%9%19%18%4
2160
11th to 20thNight
53%9%17%16%4
2168
21st to endNight
54%10%14%17%5%
2712
November1st to 10thNight
60%9%12%13%5%
2590
11th to 20thNight
61%10%11%13%5%
2660
21st to endNight
62%11%12%11%3
2964
December1st to 10thNight
59%11%12%14%5%
3040
11th to 20thNight
67%11%10%8%4
3747
21st to endNight
56%12%14%13%5%
5566

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
16%8%22%32%16%7%
180
11th to 20thDay
21%13%19%26%17%4
180
21st to endDay
24%13%23%21%15%4
198
February1st to 10thDay
23%20%25%16%12%3
226
11th to 20thDay
19%12%26%24%16%3
365
21st to endDay
13%17%31%23%11%5%
307
March1st to 10thDay
14%17%24%23%17%6%
447
11th to 20thDay
17%15%28%21%16%3
460
21st to endDay
19%17%24%18%16%7%
491
April1st to 10thDay
15%15%27%28%12%3
420
11th to 20thDay
17%14%28%21%14%6%
412
21st to endDay
18%15%28%24%12%4
420
May1st to 10thDay
17%15%26%25%13%3
423
11th to 20thDay
12%8%23%31%20%6%
553
21st to endDay
13%7%23%27%26%5%
813
June1st to 10thDay
15%9%24%29%20%3
810
11th to 20thDay
17%9%23%28%20%4
810
21st to endDay
12%5%24%29%24%6%
810
July1st to 10thDay
15%5%17%30%24%8%
796
11th to 20thDay
17%6%18%27%25%8%
638
21st to endDay
10%6%18%29%28%8%
684
August1st to 10thDay
10%6%16%30%28%10%
511
11th to 20thDay
9%6%24%30%22%9%
437
21st to endDay
14%8%27%26%18%8%
495
September1st to 10thDay
16%8%24%23%24%5%
450
11th to 20thDay
15%8%20%26%23%8%
450
21st to endDay
19%14%28%21%14%4
450
October1st to 10thDay
21%11%23%23%16%7%
450
11th to 20thDay
21%12%26%21%17%3
442
21st to endDay
21%14%26%23%13%3
228
November1st to 10thDay
36%10%21%19%8%6%
180
11th to 20thDay
23%11%23%19%18%6%
180
21st to endDay
26%10%24%26%11%3
180
December1st to 10thDay
17%7%21%28%21%6%
180
11th to 20thDay
13%10%19%33%20%4
180
21st to endDay
23%7%15%34%16%6%
198
January1st to 10thNight
24%9%24%29%11%3
956
11th to 20thNight
24%9%25%26%15%1
850
21st to endNight
24%13%23%26%12%2
935
February1st to 10thNight
26%13%17%26%15%2
774
11th to 20thNight
20%9%22%31%16%1
744
21st to endNight
18%10%21%32%16%3
628
March1st to 10thNight
18%11%23%30%16%3
760
11th to 20thNight
16%12%24%32%15%1
760
21st to endNight
15%9%17%28%26%5%
820
April1st to 10thNight
18%7%19%30%22%3
720
11th to 20thNight
15%5%22%32%19%6%
543
21st to endNight
18%6%24%30%21%1
370
May1st to 10thNight
17%7%22%33%17%4
360
11th to 20thNight
13%317%37%27%3
354
21st to endNight
15%420%31%27%3
389
June1st to 10thNight
17%5%19%34%21%3
360
11th to 20thNight
19%322%28%24%4
360
21st to endNight
12%5%18%33%30%2
360
July1st to 10thNight
13%215%37%31%1
350
11th to 20thNight
14%315%35%29%5%
348
21st to endNight
13%412%35%31%6%
394
August1st to 10thNight
9%310%32%38%7%
358
11th to 20thNight
9%215%36%32%6%
391
21st to endNight
21%413%32%27%4
594
September1st to 10thNight
17%416%34%27%3
718
11th to 20thNight
14%5%13%31%31%6%
720
21st to endNight
21%10%20%28%18%2
720
October1st to 10thNight
21%8%16%32%19%4
720
11th to 20thNight
23%7%24%28%17%2
720
21st to endNight
25%10%24%29%12%1
792
November1st to 10thNight
27%13%20%28%10%2
740
11th to 20thNight
24%13%24%27%10%1
760
21st to endNight
26%12%23%28%8%2
999
December1st to 10thNight
20%8%19%34%18%2
1040
11th to 20thNight
25%9%20%31%13%2
1040
21st to endNight
20%9%24%30%14%2
1144
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