Lacombe
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lacombe clear sky chart from 2005-11-06 to 2024-02-05.

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
40%
23493
12%
80514
8%
23441
45%
23441
18%
54502

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
36%
934
13%
4683
7%
926
41%
926
11%
3203
January11th to 20thNight
33%
940
19%
4618
8%
930
40%
930
12%
3051
January21st to endNight
32%
883
11%
4918
9%
877
41%
877
10%
3069
February1st to 10thNight
38%
738
13%
2582
12%
738
43%
738
16%
1846
February11th to 20thNight
32%
700
11%
2308
8%
700
37%
700
14%
1713
February21st to endNight
43%
592
16%
1848
15%
592
48%
592
20%
1309
March1st to 10thNight
37%
720
14%
2160
10%
720
42%
720
17%
1591
March11th to 20thNight
38%
720
16%
2003
8%
720
45%
720
21%
1438
March21st to endNight
37%
792
10%
2146
4%
792
41%
792
18%
1629
April1st to 10thNight
36%
648
12%
1728
4%
648
41%
648
20%
1275
April11th to 20thNight
36%
533
14%
1601
11%
533
40%
533
18%
1150
April21st to endNight
40%
540
11%
1620
10%
540
43%
540
23%
1084
May1st to 10thNight
36%
414
7%
1396
6%
414
39%
414
14%
1025
May11th to 20thNight
48%
354
9%
1239
7%
354
50%
354
20%
815
May21st to endNight
43%
388
2%
1358
1%
388
43%
388
17%
942
June1st to 10thNight
39%
360
0%
1260
0%
360
39%
360
14%
908
June11th to 20thNight
39%
360
0%
1260
0%
360
39%
360
13%
950
June21st to endNight
54%
360
0%
1260
0%
360
54%
360
21%
814
July1st to 10thNight
62%
350
0%
1225
0%
350
62%
350
24%
757
July11th to 20thNight
54%
348
2%
1218
0%
348
54%
348
20%
799
July21st to endNight
65%
394
7%
1302
7%
372
65%
372
28%
751
August1st to 10thNight
56%
358
7%
1410
11%
356
57%
356
19%
889
August11th to 20thNight
60%
477
11%
1545
12%
477
62%
477
25%
988
August21st to endNight
57%
594
16%
1782
13%
594
60%
594
28%
1136
September1st to 10thNight
53%
602
16%
1692
11%
602
54%
602
28%
1101
September11th to 20thNight
51%
720
17%
1980
11%
720
54%
720
29%
1282
September21st to endNight
49%
720
20%
1980
14%
720
53%
720
31%
1272
October1st to 10thNight
45%
720
16%
2074
10%
720
50%
720
24%
1399
October11th to 20thNight
39%
720
15%
2304
10%
720
46%
720
22%
1519
October21st to endNight
35%
792
16%
2574
9%
792
44%
792
18%
1779
November1st to 10thNight
32%
893
15%
2558
9%
893
38%
893
19%
1876
November11th to 20thNight
32%
950
15%
2778
8%
950
38%
950
18%
2005
November21st to endNight
32%
950
11%
2850
5%
950
37%
950
21%
1989
December1st to 10thNight
33%
950
15%
2850
9%
950
39%
950
18%
2039
December11th to 20thNight
34%
949
13%
3474
7%
949
40%
949
15%
2462
December21st to endNight
33%
1030
11%
4930
7%
1026
39%
1026
14%
2647

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
10%9%47%7%45%5%6%8%35%
77645
Night
8%10%48%7%46%6%6%8%33%
81177
TransparencyDay
45%8%16%21%8%1
77347
Night
46%8%14%21%9%2
81055
SeeingDay
13%7%24%31%19%5%
14302
Night
13%6%28%35%15%2
23556

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
411%5%11%9%5%6%5%6%8%30%
2219
11th to 20thDay
5%8%5%10%7%47%8%8%8%30%
2199
21st to endDay
5%10%48%8%445%5%10%36%
2707
February1st to 10thDay
9%12%6%9%7%446%7%9%27%
1472
11th to 20thDay
7%15%6%9%8%5%6%6%6%6%25%
1539
21st to endDay
5%10%7%12%10%5%6%7%6%7%26%
1406
March1st to 10thDay
6%12%6%11%10%5%7%6%5%7%24%
1800
11th to 20thDay
8%10%5%8%6%35%5%6%10%33%
1956
21st to endDay
11%13%6%9%7%45%5%6%8%26%
2209
April1st to 10thDay
10%10%5%8%8%46%6%7%7%29%
2232
11th to 20thDay
13%14%48%7%35%5%7%7%27%
2310
21st to endDay
14%9%37%8%45%5%5%9%31%
2340
May1st to 10thDay
12%11%5%6%6%46%6%7%9%28%
2562
11th to 20thDay
9%6%36%7%36%5%7%8%39%
2654
21st to endDay
18%7%35%6%35%5%6%8%32%
2917
June1st to 10thDay
16%7%36%6%45%6%7%8%32%
2700
11th to 20thDay
20%7%47%7%46%6%6%7%25%
2700
21st to endDay
10%435%5%5%6%6%8%10%38%
2700
July1st to 10thDay
11%6%35%6%36%6%8%9%39%
2700
11th to 20thDay
12%5%25%5%35%6%7%10%40%
2700
21st to endDay
8%425%5%45%5%7%9%47%
2938
August1st to 10thDay
11%5%25%6%45%6%7%9%41%
2521
11th to 20thDay
10%415%5%25%6%6%10%46%
2354
21st to endDay
10%6%25%5%35%5%7%9%44%
2574
September1st to 10thDay
13%6%25%5%45%5%6%8%41%
2266
11th to 20thDay
15%8%25%42346%8%42%
1980
21st to endDay
9%8%26%5%25%5%6%9%43%
1980
October1st to 10thDay
13%10%36%5%35%35%6%40%
1886
11th to 20thDay
11%8%47%6%45%5%6%6%39%
1654
21st to endDay
9%11%5%7%7%46%6%6%6%32%
1782
November1st to 10thDay
8%15%6%9%8%46%5%6%8%27%
1502
11th to 20thDay
6%12%6%10%7%45%5%47%33%
1402
21st to endDay
5%9%6%10%8%5%5%5%7%8%32%
1330
December1st to 10thDay
7%13%5%9%9%6%7%46%7%28%
1330
11th to 20thDay
411%413%8%5%6%7%6%8%28%
1682
21st to endDay
49%38%6%445%5%10%42%
2442
January1st to 10thNight
413%6%11%8%46%6%7%8%27%
4726
11th to 20thNight
48%5%10%10%5%6%7%6%7%31%
4699
21st to endNight
5%13%5%8%8%46%6%6%9%31%
4977
February1st to 10thNight
7%11%5%10%9%5%5%5%6%8%29%
2582
11th to 20thNight
7%14%5%10%10%47%7%6%8%23%
2307
21st to endNight
6%11%6%8%9%46%6%6%7%32%
1848
March1st to 10thNight
6%11%5%9%10%47%6%7%9%27%
2160
11th to 20thNight
6%9%5%9%8%46%7%8%9%29%
2003
21st to endNight
7%13%7%10%7%36%5%7%9%25%
2146
April1st to 10thNight
8%12%5%8%7%47%6%6%8%30%
1728
11th to 20thNight
11%12%49%8%45%5%6%7%28%
1601
21st to endNight
11%10%46%6%345%7%9%34%
1620
May1st to 10thNight
15%10%5%10%5%46%5%6%7%26%
1396
11th to 20thNight
10%7%46%7%45%6%6%8%37%
1239
21st to endNight
20%7%36%5%5%5%5%5%8%30%
1358
June1st to 10thNight
19%8%45%7%46%6%6%8%28%
1260
11th to 20thNight
17%9%49%6%47%8%7%7%23%
1260
21st to endNight
8%5%27%6%46%8%8%8%36%
1260
July1st to 10thNight
12%4245%346%7%11%41%
1260
11th to 20thNight
10%5%36%6%37%6%6%11%37%
1260
21st to endNight
9%4245%35%6%8%9%46%
1379
August1st to 10thNight
11%7%26%6%47%6%7%9%37%
1417
11th to 20thNight
10%6%25%6%45%6%6%10%40%
1545
21st to endNight
10%5%25%6%45%6%7%9%41%
1782
September1st to 10thNight
11%5%26%6%35%5%5%7%43%
1692
11th to 20thNight
14%6%35%43446%7%43%
1980
21st to endNight
10%7%35%6%35%45%8%44%
1980
October1st to 10thNight
10%9%38%5%35%45%8%40%
2074
11th to 20thNight
9%9%38%6%46%6%6%8%37%
2304
21st to endNight
8%12%47%7%46%6%6%9%32%
2574
November1st to 10thNight
10%14%5%8%7%45%5%6%7%29%
2558
11th to 20thNight
8%12%5%9%8%46%6%5%7%29%
2778
21st to endNight
6%10%410%8%45%6%7%9%31%
2850
December1st to 10thNight
7%11%6%10%8%45%5%5%7%31%
2850
11th to 20thNight
411%6%12%9%5%6%5%6%8%29%
3510
21st to endNight
39%47%6%35%5%7%8%43%
5214

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
50%8%12%19%10%1
2219
11th to 20thDay
47%7%9%15%18%4
2220
21st to endDay
43%7%16%27%6%1
2707
February1st to 10thDay
50%6%15%17%11%1
1472
11th to 20thDay
56%8%12%17%7%1
1548
21st to endDay
55%5%11%19%10%
1406
March1st to 10thDay
58%8%12%16%6%1
1800
11th to 20thDay
45%8%13%22%11%1
1957
21st to endDay
53%8%17%15%6%
2209
April1st to 10thDay
50%10%15%16%8%
2232
11th to 20thDay
53%7%12%20%8%
2310
21st to endDay
49%9%13%22%6%2
2340
May1st to 10thDay
51%9%15%20%6%
2562
11th to 20thDay
39%9%16%25%10%
2658
21st to endDay
48%8%14%21%9%
2918
June1st to 10thDay
47%10%17%21%6%
2700
11th to 20thDay
55%9%15%16%41
2700
21st to endDay
38%12%22%23%5%1
2700
July1st to 10thDay
38%10%22%23%5%1
2626
11th to 20thDay
38%11%24%24%3
2619
21st to endDay
32%10%25%28%6%
2775
August1st to 10thDay
38%11%23%24%5%
2503
11th to 20thDay
31%9%27%24%8%
2354
21st to endDay
34%9%21%26%9%1
2574
September1st to 10thDay
39%8%20%23%8%2
2266
11th to 20thDay
40%6%16%29%8%1
1980
21st to endDay
38%8%17%24%10%2
1980
October1st to 10thDay
44%6%17%22%9%1
1886
11th to 20thDay
43%7%17%22%10%1
1654
21st to endDay
48%8%12%21%10%1
1782
November1st to 10thDay
55%7%13%17%6%1
1502
11th to 20thDay
50%7%13%20%9%1
1402
21st to endDay
48%9%16%18%7%2
1330
December1st to 10thDay
57%6%11%15%8%2
1330
11th to 20thDay
51%10%15%17%6%1
1684
21st to endDay
37%7%12%22%18%4
2442
January1st to 10thNight
51%8%13%18%8%2
4726
11th to 20thNight
50%6%11%15%14%4
4740
21st to endNight
46%8%15%21%8%1
4977
February1st to 10thNight
53%7%11%20%10%1
2582
11th to 20thNight
55%8%12%15%9%1
2308
21st to endNight
49%7%11%20%11%2
1848
March1st to 10thNight
51%10%13%20%6%1
2160
11th to 20thNight
48%8%12%20%10%1
2003
21st to endNight
53%9%12%18%7%1
2146
April1st to 10thNight
49%9%13%18%9%1
1728
11th to 20thNight
52%6%12%21%7%2
1601
21st to endNight
43%8%17%23%8%1
1620
May1st to 10thNight
53%10%13%17%7%1
1396
11th to 20thNight
42%10%12%22%14%
1239
21st to endNight
51%7%15%18%9%1
1358
June1st to 10thNight
51%10%14%19%6%
1260
11th to 20thNight
55%10%14%15%5%1
1260
21st to endNight
40%10%19%24%6%1
1260
July1st to 10thNight
35%11%23%25%5%1
1225
11th to 20thNight
39%13%22%20%6%
1218
21st to endNight
31%11%23%28%7%
1302
August1st to 10thNight
38%12%22%22%5%
1410
11th to 20thNight
36%11%20%25%7%1
1545
21st to endNight
35%11%18%25%10%1
1782
September1st to 10thNight
38%8%16%25%10%3
1692
11th to 20thNight
39%6%16%27%9%3
1980
21st to endNight
37%7%15%25%13%3
1980
October1st to 10thNight
43%7%16%22%11%1
2074
11th to 20thNight
43%7%16%23%9%1
2304
21st to endNight
47%8%16%20%8%1
2574
November1st to 10thNight
52%7%13%20%7%1
2558
11th to 20thNight
51%7%13%18%9%1
2778
21st to endNight
47%7%18%18%7%2
2850
December1st to 10thNight
51%6%10%20%10%2
2850
11th to 20thNight
51%8%15%20%6%
3507
21st to endNight
37%6%13%24%15%5%
5214

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
5%8%26%36%17%8%
180
11th to 20thDay
7%6%29%36%18%4
180
21st to endDay
9%9%28%28%19%7%
198
February1st to 10thDay
16%8%23%33%14%5%
168
11th to 20thDay
15%6%33%33%11%2
224
21st to endDay
7%429%37%15%7%
272
March1st to 10thDay
10%10%34%26%16%4
420
11th to 20thDay
9%7%32%32%14%6%
420
21st to endDay
16%6%30%26%16%5%
462
April1st to 10thDay
12%10%33%29%10%5%
420
11th to 20thDay
19%10%23%29%13%6%
412
21st to endDay
18%8%26%32%14%3
420
May1st to 10thDay
15%10%22%31%17%4
521
11th to 20thDay
10%7%20%38%21%4
625
21st to endDay
17%421%30%20%8%
679
June1st to 10thDay
18%6%22%36%15%3
630
11th to 20thDay
22%7%22%27%17%4
630
21st to endDay
12%321%30%25%9%
630
July1st to 10thDay
14%5%15%34%24%9%
621
11th to 20thDay
15%6%17%34%23%5%
618
21st to endDay
8%419%33%29%9%
684
August1st to 10thDay
12%5%18%32%23%9%
461
11th to 20thDay
9%5%21%33%27%6%
437
21st to endDay
11%7%17%31%24%9%
495
September1st to 10thDay
15%8%28%28%20%2
450
11th to 20thDay
20%6%24%26%20%4
450
21st to endDay
11%12%28%29%16%4
450
October1st to 10thDay
19%6%24%29%14%8%
356
11th to 20thDay
10%11%30%31%14%3
270
21st to endDay
14%13%34%27%11%1
297
November1st to 10thDay
16%8%28%31%12%5%
270
11th to 20thDay
14%6%36%32%12%1
214
21st to endDay
6%9%36%29%12%8%
180
December1st to 10thDay
11%6%35%26%17%7%
180
11th to 20thDay
11%7%35%28%18%1
180
21st to endDay
9%7%23%36%21%5%
198
January1st to 10thNight
11%6%34%33%14%2
950
11th to 20thNight
13%8%32%35%12%2
950
21st to endNight
13%10%29%34%12%2
899
February1st to 10thNight
11%10%25%34%18%2
738
11th to 20thNight
13%5%34%34%14%1
704
21st to endNight
10%426%39%17%5%
592
March1st to 10thNight
10%431%37%14%3
720
11th to 20thNight
10%5%32%35%15%3
720
21st to endNight
15%5%27%37%14%3
792
April1st to 10thNight
13%7%31%32%16%2
648
11th to 20thNight
16%8%27%38%11%1
533
21st to endNight
16%7%27%35%14%1
540
May1st to 10thNight
18%7%24%37%12%2
414
11th to 20thNight
13%5%26%34%20%1
354
21st to endNight
23%6%20%34%15%3
389
June1st to 10thNight
21%7%23%33%15%2
360
11th to 20thNight
23%424%34%15%1
360
21st to endNight
11%322%40%22%3
360
July1st to 10thNight
14%213%47%23%2
350
11th to 20thNight
11%319%42%23%1
348
21st to endNight
9%6%14%40%29%2
394
August1st to 10thNight
13%318%34%29%3
358
11th to 20thNight
11%5%15%43%24%2
477
21st to endNight
11%320%41%25%1
594
September1st to 10thNight
13%420%41%19%2
602
11th to 20thNight
17%321%40%18%1
720
21st to endNight
13%427%38%17%2
720
October1st to 10thNight
15%427%37%15%2
720
11th to 20thNight
15%6%30%34%13%2
720
21st to endNight
14%9%32%34%12%
792
November1st to 10thNight
15%8%33%32%11%1
893
11th to 20thNight
12%8%36%31%10%2
950
21st to endNight
11%5%39%33%11%2
950
December1st to 10thNight
13%7%32%31%13%3
950
11th to 20thNight
9%7%35%35%12%2
950
21st to endNight
12%336%33%15%2
1045
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