Penticton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Penticton clear sky chart from 2005-11-05 to 2018-02-14.

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%
15356
11%
48561
9%
15326
46%
15326
17%
34592

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
30%
780
6%
2716
5%
776
32%
776
8%
2212
January16th to endNight
32%
832
7%
2912
6%
832
35%
832
11%
2258
February1st to 15thNight
35%
756
8%
2564
7%
754
38%
754
11%
1972
February16th to endNight
39%
632
10%
1963
8%
632
42%
632
15%
1462
March1st to 15thNight
31%
720
7%
2160
5%
720
35%
720
12%
1705
March16th to endNight
35%
768
9%
2001
4%
768
38%
768
14%
1582
April1st to 15thNight
43%
719
9%
1799
4%
719
45%
719
19%
1365
April16th to endNight
43%
514
12%
1594
9%
514
46%
514
18%
1134
May1st to 15thNight
51%
359
13%
1439
17%
359
58%
359
21%
862
May16th to endNight
55%
374
7%
1496
11%
374
56%
374
17%
999
June1st to 15thNight
50%
360
5%
1233
2%
360
51%
360
19%
822
June16th to endNight
53%
360
8%
1081
1%
360
53%
360
26%
702
July1st to 15thNight
67%
340
9%
1251
6%
340
69%
340
35%
633
July16th to endNight
71%
376
18%
1416
24%
354
78%
354
45%
585
August1st to 15thNight
76%
360
22%
1432
30%
358
79%
358
37%
656
August16th to endNight
66%
642
25%
1788
19%
642
69%
642
44%
980
September1st to 15thNight
66%
720
24%
1800
12%
720
70%
720
45%
1039
September16th to endNight
59%
716
23%
1941
16%
716
62%
716
32%
1223
October1st to 15thNight
53%
720
14%
2160
13%
720
56%
720
24%
1431
October16th to endNight
42%
768
12%
2468
9%
768
48%
768
17%
1768
November1st to 15thNight
30%
760
8%
2587
7%
760
32%
760
10%
2054
November16th to endNight
25%
820
6%
2770
3%
820
29%
820
8%
2268
December1st to 15thNight
33%
975
8%
2925
6%
975
34%
975
12%
2331
December16th to endNight
25%
985
7%
3065
4%
985
29%
985
8%
2549

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
8%8%37%6%36%5%5%7%36%
49528
Night
7%9%47%6%35%5%5%7%34%
48724
Cloud CoverDay
9%9%47%6%45%5%5%7%34%
49528
Night
9%10%47%6%35%5%5%7%33%
48728
TransparencyDay
49%9%13%17%8%1
49194
Night
49%8%13%18%8%1
48562
SeeingDay
16%16%29%23%11%2
6380
Night
15%9%23%30%17%3
15362

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
10%12%6%11%8%46%6%6%9%16%
1552
16th to endDay
7%14%7%10%8%35%6%6%6%23%
1664
February1st to 15thDay
6%11%6%10%9%46%7%46%24%
1598
16th to endDay
6%11%49%9%46%7%7%7%25%
1511
March1st to 15thDay
7%11%5%8%7%45%7%7%9%25%
1800
16th to endDay
6%12%5%9%9%5%7%5%6%8%23%
2220
April1st to 15thDay
9%11%46%8%5%7%6%5%7%26%
2149
16th to endDay
8%11%37%6%36%5%6%8%30%
2365
May1st to 15thDay
9%8%26%6%36%6%5%8%36%
2511
16th to endDay
12%8%37%6%36%6%5%8%31%
2615
June1st to 15thDay
15%6%36%7%35%5%5%6%32%
2721
16th to endDay
12%426%6%46%6%6%7%35%
2876
July1st to 15thDay
5%3235%35%45%6%54%
2631
16th to endDay
431342445%6%60%
2657
August1st to 15thDay
3212435%45%9%57%
2520
16th to endDay
5%313435%45%7%54%
2413
September1st to 15thDay
5%313423445%60%
2160
16th to endDay
9%5%25%435%5%5%8%45%
2017
October1st to 15thDay
8%7%25%6%46%5%6%5%41%
1800
16th to endDay
10%10%48%6%35%5%5%6%31%
1755
November1st to 15thDay
12%11%48%8%46%5%6%7%22%
1602
16th to endDay
8%12%8%10%7%47%5%6%5%22%
1505
December1st to 15thDay
6%13%5%12%8%38%7%6%7%20%
1365
16th to endDay
8%14%6%12%8%45%6%5%6%18%
1521
January1st to 15thNight
10%15%8%12%9%45%5%5%6%15%
2716
16th to endNight
7%15%6%10%9%46%5%6%6%19%
2912
February1st to 15thNight
9%13%5%9%9%45%5%5%6%25%
2552
16th to endNight
6%12%48%6%35%7%6%7%31%
1963
March1st to 15thNight
7%10%5%8%7%5%6%47%8%28%
2160
16th to endNight
7%8%48%8%46%5%6%8%30%
1997
April1st to 15thNight
8%7%37%5%45%5%6%10%35%
1799
16th to endNight
7%8%36%6%46%5%6%8%36%
1594
May1st to 15thNight
9%5%15%435%5%6%7%45%
1439
16th to endNight
10%6%35%445%6%6%10%36%
1496
June1st to 15thNight
11%6%35%5%25%6%5%9%39%
1233
16th to endNight
7%415%5%345%6%7%47%
1081
July1st to 15thNight
322325%46%6%60%
1326
16th to endNight
31122335%6%68%
1512
August1st to 15thNight
421222335%7%64%
1440
16th to endNight
22133235%5%8%61%
1788
September1st to 15thNight
4212314446%63%
1800
16th to endNight
6%5%2442445%8%51%
1941
October1st to 15thNight
7%6%26%5%35%5%5%5%45%
2160
16th to endNight
11%9%36%5%35%6%6%7%33%
2468
November1st to 15thNight
11%12%5%9%7%36%5%5%6%25%
2587
16th to endNight
8%15%6%9%8%5%6%5%5%6%21%
2770
December1st to 15thNight
6%14%7%12%9%46%5%5%8%19%
2925
16th to endNight
9%17%6%12%9%5%6%5%6%6%16%
3065

Percentage Cloud Cover SW (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%13%6%10%7%5%8%5%5%7%17%
1552
16th to endDay
8%15%6%10%7%4447%6%22%
1664
February1st to 15thDay
9%13%7%10%7%36%5%46%23%
1598
16th to endDay
6%12%5%10%8%47%6%6%7%24%
1511
March1st to 15thDay
9%13%49%7%47%5%6%8%22%
1800
16th to endDay
8%14%5%11%8%46%6%6%7%19%
2220
April1st to 15thDay
9%12%5%9%8%5%6%6%6%7%22%
2149
16th to endDay
9%12%38%7%45%6%5%7%27%
2365
May1st to 15thDay
9%9%46%6%45%6%6%7%34%
2511
16th to endDay
13%8%37%7%5%7%5%5%6%27%
2615
June1st to 15thDay
15%7%46%8%35%45%7%31%
2721
16th to endDay
11%6%36%7%36%6%7%8%32%
2876
July1st to 15thDay
5%424425%447%53%
2631
16th to endDay
331343445%5%60%
2657
August1st to 15thDay
32134245%6%9%55%
2520
16th to endDay
5%413335%46%8%52%
2413
September1st to 15thDay
5%414423346%58%
2160
16th to endDay
10%6%245%35%46%8%42%
2017
October1st to 15thDay
9%8%35%5%5%5%5%5%6%37%
1800
16th to endDay
14%11%48%5%36%35%6%31%
1755
November1st to 15thDay
15%13%410%5%5%5%6%6%5%21%
1602
16th to endDay
9%15%8%10%6%36%6%6%5%20%
1505
December1st to 15thDay
7%13%5%10%8%47%8%5%7%20%
1365
16th to endDay
11%13%6%13%8%47%6%45%18%
1521
January1st to 15thNight
13%15%6%11%8%46%5%5%7%15%
2716
16th to endNight
10%14%6%9%8%46%5%6%6%21%
2912
February1st to 15thNight
12%14%48%7%36%45%6%24%
2552
16th to endNight
6%14%49%7%35%5%5%7%30%
1963
March1st to 15thNight
8%11%5%9%8%46%5%5%8%25%
2160
16th to endNight
7%10%310%7%5%6%5%6%7%27%
2001
April1st to 15thNight
8%8%38%6%36%6%7%9%32%
1799
16th to endNight
6%9%46%7%46%5%7%9%33%
1594
May1st to 15thNight
8%7%235%25%5%6%7%44%
1439
16th to endNight
10%8%25%6%36%6%6%9%33%
1496
June1st to 15thNight
11%6%35%5%35%6%6%8%37%
1233
16th to endNight
8%315%5%36%5%6%7%45%
1081
July1st to 15thNight
33134235%6%7%59%
1326
16th to endNight
31131335%7%68%
1512
August1st to 15thNight
42123235%46%63%
1440
16th to endNight
231332346%8%59%
1788
September1st to 15thNight
421332445%6%61%
1800
16th to endNight
7%6%2432345%8%49%
1941
October1st to 15thNight
8%7%36%5%35%5%5%6%43%
2160
16th to endNight
13%10%36%6%35%5%5%7%32%
2468
November1st to 15thNight
15%12%5%8%7%45%45%6%23%
2587
16th to endNight
11%15%8%10%8%346%5%5%20%
2770
December1st to 15thNight
9%14%6%10%8%5%6%45%7%20%
2925
16th to endNight
11%18%6%10%7%45%6%6%6%16%
3065

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
65%9%12%9%3
1552
16th to endDay
58%9%13%14%31
1664
February1st to 15thDay
61%9%12%11%3
1598
16th to endDay
60%9%13%11%5%
1511
March1st to 15thDay
61%11%12%11%2
1800
16th to endDay
65%10%13%8%2
2220
April1st to 15thDay
62%10%12%11%2
2149
16th to endDay
54%11%12%16%4
2365
May1st to 15thDay
50%7%15%18%7%
2511
16th to endDay
57%9%12%16%3
2619
June1st to 15thDay
54%9%12%14%7%2
2721
16th to endDay
48%10%13%16%10%
2876
July1st to 15thDay
31%6%12%23%19%6%
2477
16th to endDay
26%7%13%25%23%4
2490
August1st to 15thDay
25%8%15%29%16%4
2503
16th to endDay
28%8%14%29%16%2
2413
September1st to 15thDay
27%6%14%26%22%2
2160
16th to endDay
39%9%14%22%11%2
2017
October1st to 15thDay
46%8%14%21%7%
1800
16th to endDay
53%9%14%18%4
1755
November1st to 15thDay
62%11%10%11%31
1602
16th to endDay
62%10%10%11%4
1505
December1st to 15thDay
56%11%14%14%3
1365
16th to endDay
64%10%11%10%3
1521
January1st to 15thNight
66%7%12%9%3
2716
16th to endNight
59%8%14%11%4
2912
February1st to 15thNight
59%7%14%12%4
2564
16th to endNight
53%8%15%15%5%
1963
March1st to 15thNight
59%8%14%13%3
2160
16th to endNight
55%10%14%15%3
2001
April1st to 15thNight
48%11%16%18%5%
1799
16th to endNight
46%10%15%22%5%
1594
May1st to 15thNight
36%9%16%22%13%
1440
16th to endNight
45%9%18%21%4
1496
June1st to 15thNight
43%8%13%23%8%1
1233
16th to endNight
35%11%15%24%11%
1081
July1st to 15thNight
23%8%13%27%21%5%
1251
16th to endNight
17%415%29%29%4
1416
August1st to 15thNight
22%5%13%32%21%4
1432
16th to endNight
21%8%14%33%18%2
1788
September1st to 15thNight
22%7%13%29%22%4
1800
16th to endNight
32%9%13%27%14%3
1941
October1st to 15thNight
41%8%15%23%10%
2160
16th to endNight
50%7%15%20%5%
2468
November1st to 15thNight
62%8%11%12%31
2587
16th to endNight
65%8%10%11%4
2770
December1st to 15thNight
60%8%12%14%2
2925
16th to endNight
64%10%9%10%3
3065

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
17%5%14%28%24%8%
90
16th to endDay
17%20%31%23%5%1
96
February1st to 15thDay
22%18%31%22%31
180
16th to endDay
17%20%32%19%8%1
227
March1st to 15thDay
20%35%28%11%3
270
16th to endDay
23%29%29%13%2
288
April1st to 15thDay
24%23%25%18%5%2
269
16th to endDay
21%22%31%14%7%2
270
May1st to 15thDay
19%19%33%19%6%1
288
16th to endDay
20%14%23%20%16%4
330
June1st to 15thDay
16%13%24%26%16%2
516
16th to endDay
14%11%30%26%14%1
671
July1st to 15thDay
8%12%30%33%14%1
411
16th to endDay
414%32%30%13%4
327
August1st to 15thDay
7%7%28%32%18%5%
315
16th to endDay
9%11%31%31%10%4
332
September1st to 15thDay
8%15%29%28%13%4
315
16th to endDay
17%12%31%20%13%3
315
October1st to 15thDay
18%21%29%21%8%
315
16th to endDay
23%9%28%23%12%1
171
November1st to 15thDay
32%18%22%19%5%1
108
16th to endDay
20%17%28%15%10%7%
90
December1st to 15thDay
7%14%23%25%21%7%
90
16th to endDay
11%11%41%26%6%3
96
January1st to 15thNight
23%12%23%27%12%1
780
16th to endNight
16%11%27%30%12%1
832
February1st to 15thNight
20%10%21%32%12%1
760
16th to endNight
13%11%25%28%17%2
632
March1st to 15thNight
15%15%29%24%11%2
720
16th to endNight
14%14%27%30%11%2
768
April1st to 15thNight
12%10%25%31%17%3
719
16th to endNight
11%10%28%33%14%1
514
May1st to 15thNight
13%6%22%34%20%2
360
16th to endNight
14%5%20%26%28%4
375
June1st to 15thNight
13%7%22%30%25%
360
16th to endNight
8%5%23%38%21%2
360
July1st to 15thNight
5%418%34%34%3
340
16th to endNight
3418%38%32%3
376
August1st to 15thNight
6%110%29%45%6%
360
16th to endNight
7%316%35%32%4
642
September1st to 15thNight
5%6%15%29%30%11%
720
16th to endNight
11%5%18%31%27%5%
716
October1st to 15thNight
14%7%17%35%20%3
720
16th to endNight
20%9%20%31%14%3
768
November1st to 15thNight
25%13%25%24%9%1
760
16th to endNight
21%13%28%23%10%3
820
December1st to 15thNight
19%9%24%32%11%1
975
16th to endNight
23%10%28%29%6%
985
Page generated at 2018-02-15 07:58:49. Version ac04

Copyright 2018 A. Danko


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