Cold Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cold Lake clear sky chart from 2005-11-06 to 2026-08-30.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	10% 9% 3 9% 6% 5% 5% 4 7% 8% 35%	148420
	Night	8% 10% 4 10% 6% 6% 6% 4 6% 8% 32%	142443
Transparency	Day	45% 7% 16% 24% 7%	148117
	Night	49% 7% 15% 21% 8%	142331
Seeing	Day	13% 8% 28% 30% 17% 5%	18067
	Night	13% 6% 29% 35% 15% 2	26969

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	6% 13% 6% 16% 9% 7% 7% 4 5% 6% 21%	4125
	11th to 20th	Day	4 8% 3 10% 6% 7% 8% 5% 7% 10% 30%	4119
	21st to end	Day	6% 14% 6% 14% 8% 5% 4 4 6% 7% 26%	4531
February	1st to 10th	Day	6% 13% 5% 11% 9% 7% 6% 5% 7% 7% 24%	1669
	11th to 20th	Day	6% 9% 5% 12% 8% 7% 6% 5% 7% 8% 27%	1845
	21st to end	Day	6% 11% 4 12% 8% 8% 6% 5% 8% 8% 25%	1557
March	1st to 10th	Day	5% 8% 3 9% 6% 6% 7% 6% 8% 11% 32%	4587
	11th to 20th	Day	6% 9% 4 10% 8% 6% 6% 4 7% 9% 31%	5109
	21st to end	Day	10% 15% 5% 11% 6% 4 5% 3 5% 6% 30%	5649
April	1st to 10th	Day	8% 12% 4 8% 6% 6% 5% 5% 7% 8% 33%	2625
	11th to 20th	Day	12% 11% 3 8% 6% 6% 6% 4 6% 7% 31%	2700
	21st to end	Day	12% 11% 3 9% 5% 5% 5% 4 6% 7% 32%	2850
May	1st to 10th	Day	9% 7% 3 8% 6% 6% 6% 5% 6% 7% 38%	8394
	11th to 20th	Day	18% 11% 3 7% 5% 5% 6% 4 6% 7% 29%	8755
	21st to end	Day	10% 7% 3 8% 5% 5% 6% 4 7% 9% 36%	9764
June	1st to 10th	Day	16% 6% 3 8% 5% 5% 6% 5% 7% 8% 31%	3360
	11th to 20th	Day	19% 9% 3 9% 5% 6% 5% 5% 8% 7% 25%	3360
	21st to end	Day	12% 8% 3 8% 5% 6% 6% 4 7% 8% 33%	3360
July	1st to 10th	Day	8% 6% 2 7% 5% 5% 6% 5% 7% 10% 39%	9128
	11th to 20th	Day	9% 5% 2 6% 4 4 5% 5% 7% 10% 43%	8820
	21st to end	Day	9% 4 2 6% 5% 5% 5% 5% 8% 9% 43%	9569
August	1st to 10th	Day	11% 6% 3 7% 4 4 4 4 5% 7% 45%	4998
	11th to 20th	Day	9% 5% 2 7% 5% 5% 5% 5% 7% 9% 41%	4395
	21st to end	Day	9% 5% 2 6% 4 4 4 4 6% 8% 47%	4782
September	1st to 10th	Day	12% 7% 2 7% 4 4 4 4 5% 8% 42%	2490
	11th to 20th	Day	16% 8% 2 6% 4 3 4 3 5% 8% 42%	2312
	21st to end	Day	9% 6% 2 7% 5% 4 5% 4 7% 8% 42%	2168
October	1st to 10th	Day	10% 9% 3 7% 5% 4 5% 4 6% 8% 38%	3270
	11th to 20th	Day	12% 9% 3 8% 5% 5% 4 4 7% 9% 35%	3168
	21st to end	Day	8% 14% 5% 9% 6% 5% 6% 5% 6% 7% 30%	2912
November	1st to 10th	Day	11% 15% 4 12% 6% 6% 5% 3 5% 7% 25%	1648
	11th to 20th	Day	9% 13% 5% 13% 7% 5% 7% 5% 7% 6% 23%	1612
	21st to end	Day	6% 12% 4 13% 7% 7% 6% 4 5% 7% 28%	1368
December	1st to 10th	Day	6% 12% 5% 17% 10% 6% 6% 5% 7% 7% 19%	2020
	11th to 20th	Day	8% 16% 6% 15% 7% 6% 5% 4 5% 7% 21%	2319
	21st to end	Day	3 10% 5% 12% 8% 6% 6% 5% 6% 6% 33%	3082
January	1st to 10th	Night	6% 11% 6% 15% 9% 7% 7% 4 6% 7% 20%	8768
	11th to 20th	Night	4 8% 3 9% 7% 7% 8% 5% 7% 10% 31%	8779
	21st to end	Night	6% 11% 6% 12% 8% 6% 6% 4 6% 8% 28%	9650
February	1st to 10th	Night	7% 12% 4 12% 8% 7% 6% 5% 6% 7% 25%	2972
	11th to 20th	Night	6% 11% 4 10% 7% 7% 5% 4 6% 8% 32%	2662
	21st to end	Night	3 10% 5% 10% 8% 7% 7% 6% 7% 7% 29%	2249
March	1st to 10th	Night	5% 10% 4 13% 7% 7% 6% 5% 7% 10% 26%	5505
	11th to 20th	Night	6% 11% 4 10% 6% 6% 7% 5% 7% 8% 30%	5110
	21st to end	Night	9% 16% 5% 10% 6% 5% 5% 4 5% 7% 28%	5566
April	1st to 10th	Night	7% 10% 3 10% 6% 6% 5% 4 7% 9% 35%	1992
	11th to 20th	Night	9% 9% 3 9% 6% 5% 5% 4 7% 8% 33%	1871
	21st to end	Night	13% 11% 4 8% 5% 4 3 5% 5% 6% 36%	1769
May	1st to 10th	Night	9% 8% 3 6% 4 4 4 4 5% 8% 43%	4531
	11th to 20th	Night	19% 10% 3 9% 5% 5% 5% 4 5% 6% 29%	4105
	21st to end	Night	11% 8% 3 7% 5% 5% 6% 4 7% 9% 35%	4406
June	1st to 10th	Night	17% 7% 4 7% 5% 4 5% 4 7% 7% 33%	1260
	11th to 20th	Night	17% 10% 2 8% 6% 6% 6% 4 7% 9% 25%	1260
	21st to end	Night	12% 5% 2 6% 5% 5% 6% 5% 7% 9% 38%	1260
July	1st to 10th	Night	6% 3 2 5% 4 4 5% 5% 9% 11% 47%	3815
	11th to 20th	Night	7% 5% 2 5% 5% 4 4 4 6% 9% 49%	4140
	21st to end	Night	11% 5% 2 6% 4 4 4 4 7% 8% 43%	4499
August	1st to 10th	Night	11% 6% 3 6% 4 4 5% 4 7% 7% 44%	2373
	11th to 20th	Night	8% 4 2 7% 5% 5% 6% 5% 8% 10% 40%	2882
	21st to end	Night	8% 5% 2 6% 5% 4 5% 5% 6% 7% 46%	3326
September	1st to 10th	Night	13% 6% 2 6% 3 4 4 4 6% 8% 45%	1910
	11th to 20th	Night	11% 7% 2 6% 5% 4 4 4 6% 8% 44%	2085
	21st to end	Night	9% 6% 2 5% 4 4 6% 4 7% 9% 45%	2231
October	1st to 10th	Night	8% 7% 3 7% 5% 5% 5% 4 7% 8% 42%	3920
	11th to 20th	Night	10% 8% 3 7% 5% 4 5% 4 6% 9% 39%	3977
	21st to end	Night	11% 13% 5% 9% 5% 5% 6% 4 6% 8% 28%	4856
November	1st to 10th	Night	12% 16% 6% 9% 7% 5% 5% 4 5% 6% 25%	2870
	11th to 20th	Night	9% 13% 5% 14% 7% 5% 5% 4 6% 6% 24%	3007
	21st to end	Night	6% 13% 6% 13% 8% 6% 5% 4 7% 7% 26%	3250
December	1st to 10th	Night	9% 14% 5% 16% 7% 7% 5% 4 6% 7% 20%	5380
	11th to 20th	Night	6% 15% 6% 17% 8% 6% 6% 4 6% 7% 18%	6093
	21st to end	Night	3 9% 5% 14% 8% 6% 5% 4 5% 5% 35%	8114

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	63% 4 9% 19% 5%	4125
	11th to 20th	Day	49% 6% 16% 17% 11% 1	4140
	21st to end	Day	58% 6% 17% 12% 7%	4531
February	1st to 10th	Day	55% 9% 12% 13% 11%	1669
	11th to 20th	Day	52% 7% 14% 18% 8%	1854
	21st to end	Day	54% 6% 15% 18% 7%	1557
March	1st to 10th	Day	42% 7% 21% 24% 6%	4587
	11th to 20th	Day	46% 8% 15% 23% 8%	5110
	21st to end	Day	52% 7% 10% 19% 12%	5649
April	1st to 10th	Day	47% 7% 17% 19% 9%	2625
	11th to 20th	Day	51% 6% 13% 19% 9% 1	2700
	21st to end	Day	49% 6% 12% 22% 8% 1	2850
May	1st to 10th	Day	43% 6% 11% 26% 12% 2	8394
	11th to 20th	Day	51% 7% 9% 25% 7%	8759
	21st to end	Day	41% 9% 16% 24% 8% 1	9765
June	1st to 10th	Day	47% 10% 15% 18% 9% 1	3360
	11th to 20th	Day	55% 9% 13% 18% 4 1	3360
	21st to end	Day	46% 10% 15% 23% 6% 1	3360
July	1st to 10th	Day	37% 8% 26% 25% 4	9053
	11th to 20th	Day	34% 7% 15% 32% 12%	8739
	21st to end	Day	32% 9% 21% 33% 5%	9362
August	1st to 10th	Day	37% 8% 22% 31% 2	4980
	11th to 20th	Day	37% 9% 25% 24% 5%	4437
	21st to end	Day	34% 7% 26% 30% 4	4781
September	1st to 10th	Day	39% 8% 18% 26% 8% 1	2490
	11th to 20th	Day	42% 7% 20% 26% 5%	2312
	21st to end	Day	38% 8% 19% 24% 10% 1	2168
October	1st to 10th	Day	44% 6% 19% 27% 4	3270
	11th to 20th	Day	46% 6% 17% 26% 5%	3168
	21st to end	Day	56% 7% 18% 16% 3	2912
November	1st to 10th	Day	61% 8% 12% 14% 5%	1648
	11th to 20th	Day	62% 8% 14% 13% 4	1612
	21st to end	Day	58% 8% 13% 16% 4 1	1368
December	1st to 10th	Day	64% 7% 10% 15% 3 1	2020
	11th to 20th	Day	65% 6% 12% 14% 4	2320
	21st to end	Day	51% 5% 14% 23% 7% 1	3082
January	1st to 10th	Night	61% 6% 10% 14% 8%	8769
	11th to 20th	Night	49% 5% 17% 18% 11% 1	8820
	21st to end	Night	55% 6% 19% 13% 7%	9650
February	1st to 10th	Night	55% 7% 12% 16% 9%	2972
	11th to 20th	Night	49% 6% 12% 22% 11%	2663
	21st to end	Night	51% 8% 14% 17% 10%	2249
March	1st to 10th	Night	51% 6% 17% 18% 7%	5505
	11th to 20th	Night	46% 9% 16% 23% 6%	5110
	21st to end	Night	53% 5% 11% 17% 14%	5566
April	1st to 10th	Night	45% 7% 14% 20% 13%	1992
	11th to 20th	Night	45% 7% 12% 19% 13% 3	1871
	21st to end	Night	47% 7% 12% 21% 11% 2	1769
May	1st to 10th	Night	39% 4 8% 31% 17% 1	4531
	11th to 20th	Night	53% 6% 8% 26% 7% 1	4105
	21st to end	Night	41% 9% 16% 25% 8% 1	4410
June	1st to 10th	Night	48% 7% 14% 18% 11% 2	1260
	11th to 20th	Night	52% 11% 14% 16% 7%	1260
	21st to end	Night	40% 9% 17% 22% 10% 1	1260
July	1st to 10th	Night	29% 8% 27% 29% 6%	3781
	11th to 20th	Night	31% 7% 14% 34% 14%	4098
	21st to end	Night	37% 7% 21% 29% 5%	4401
August	1st to 10th	Night	37% 7% 19% 35% 2	2366
	11th to 20th	Night	35% 9% 28% 23% 5%	2906
	21st to end	Night	36% 6% 22% 31% 4	3326
September	1st to 10th	Night	38% 6% 20% 26% 8% 2	1910
	11th to 20th	Night	39% 7% 19% 26% 8%	2085
	21st to end	Night	34% 8% 17% 30% 9% 2	2231
October	1st to 10th	Night	39% 5% 21% 28% 6%	3920
	11th to 20th	Night	42% 5% 17% 29% 6%	3977
	21st to end	Night	55% 6% 18% 17% 4	4856
November	1st to 10th	Night	62% 7% 10% 16% 5%	2870
	11th to 20th	Night	61% 8% 13% 12% 5%	3007
	21st to end	Night	58% 8% 15% 15% 4	3250
December	1st to 10th	Night	64% 6% 12% 12% 5%	5380
	11th to 20th	Night	65% 7% 15% 10% 3	6091
	21st to end	Night	49% 5% 12% 22% 10% 1	8114

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	11% 4 27% 35% 17% 6%	220
	11th to 20th	Day	14% 7% 29% 35% 11% 5%	220
	21st to end	Day	9% 11% 33% 36% 7% 3	242
February	1st to 10th	Day	9% 6% 36% 34% 11% 3	245
	11th to 20th	Day	7% 7% 30% 31% 21% 5%	330
	21st to end	Day	7% 7% 31% 38% 14% 3	273
March	1st to 10th	Day	10% 8% 35% 34% 13% 1	440
	11th to 20th	Day	11% 10% 37% 27% 12% 3	540
	21st to end	Day	16% 6% 32% 31% 12% 2	594
April	1st to 10th	Day	10% 11% 34% 31% 12% 2	540
	11th to 20th	Day	17% 10% 31% 28% 11% 3	532
	21st to end	Day	14% 9% 32% 30% 12% 3	660
May	1st to 10th	Day	10% 10% 28% 29% 18% 4	753
	11th to 20th	Day	12% 7% 25% 30% 19% 7%	775
	21st to end	Day	16% 7% 23% 29% 20% 6%	844
June	1st to 10th	Day	18% 10% 29% 27% 12% 4	780
	11th to 20th	Day	20% 9% 24% 25% 16% 5%	780
	21st to end	Day	12% 6% 21% 31% 21% 10%	780
July	1st to 10th	Day	12% 5% 22% 30% 25% 6%	771
	11th to 20th	Day	10% 5% 23% 34% 21% 7%	768
	21st to end	Day	8% 5% 24% 30% 24% 9%	849
August	1st to 10th	Day	13% 5% 17% 29% 26% 9%	776
	11th to 20th	Day	12% 6% 22% 33% 23% 4	628
	21st to end	Day	10% 7% 22% 31% 22% 8%	620
September	1st to 10th	Day	13% 11% 28% 27% 17% 4	530
	11th to 20th	Day	19% 6% 22% 30% 18% 5%	530
	21st to end	Day	11% 12% 33% 29% 12% 3	498
October	1st to 10th	Day	12% 8% 30% 32% 15% 3	330
	11th to 20th	Day	18% 9% 35% 27% 11% 1	330
	21st to end	Day	18% 13% 30% 26% 10% 2	363
November	1st to 10th	Day	17% 11% 27% 31% 12% 2	330
	11th to 20th	Day	14% 9% 43% 26% 5% 3	294
	21st to end	Day	10% 9% 34% 30% 12% 5%	220
December	1st to 10th	Day	8% 6% 34% 36% 14% 2	220
	11th to 20th	Day	11% 7% 41% 31% 8%	220
	21st to end	Day	10% 5% 29% 33% 19% 6%	242
January	1st to 10th	Night	12% 5% 29% 37% 15% 2	1050
	11th to 20th	Night	11% 6% 32% 38% 12% 2	1050
	21st to end	Night	13% 8% 36% 31% 9% 2	1155
February	1st to 10th	Night	11% 6% 26% 39% 16% 2	919
	11th to 20th	Night	11% 4 32% 35% 16% 2	824
	21st to end	Night	7% 4 25% 43% 18% 3	692
March	1st to 10th	Night	10% 4 32% 40% 13% 1	840
	11th to 20th	Night	13% 6% 31% 37% 13% 2	840
	21st to end	Night	13% 8% 26% 36% 15% 2	905
April	1st to 10th	Night	9% 5% 30% 40% 15% 1	630
	11th to 20th	Night	13% 7% 32% 33% 13% 2	623
	21st to end	Night	18% 7% 27% 33% 15% 1	630
May	1st to 10th	Night	13% 9% 26% 35% 16% 1	565
	11th to 20th	Night	14% 4 25% 38% 16% 3	414
	21st to end	Night	15% 4 22% 36% 19% 3	455
June	1st to 10th	Night	18% 7% 25% 31% 18% 1	420
	11th to 20th	Night	20% 6% 20% 30% 22% 2	420
	21st to end	Night	13% 1 19% 34% 29% 4	420
July	1st to 10th	Night	11% 3 19% 37% 30%	410
	11th to 20th	Night	11% 2 19% 41% 24% 2	408
	21st to end	Night	10% 3 18% 41% 23% 5%	460
August	1st to 10th	Night	11% 1 18% 36% 28% 6%	428
	11th to 20th	Night	10% 3 19% 40% 26% 2	624
	21st to end	Night	10% 3 23% 38% 23% 2	687
September	1st to 10th	Night	17% 3 25% 32% 21% 1	600
	11th to 20th	Night	12% 5% 23% 38% 20% 1	685
	21st to end	Night	11% 6% 32% 36% 14% 1	800
October	1st to 10th	Night	16% 6% 31% 35% 11% 2	800
	11th to 20th	Night	15% 6% 31% 33% 13% 2	800
	21st to end	Night	17% 10% 33% 30% 9% 1	1035
November	1st to 10th	Night	19% 7% 31% 32% 9% 2	1025
	11th to 20th	Night	16% 6% 33% 32% 10% 3	1050
	21st to end	Night	11% 6% 38% 33% 10% 1	1050
December	1st to 10th	Night	14% 5% 33% 31% 14% 3	1050
	11th to 20th	Night	12% 7% 33% 37% 9% 2	1050
	21st to end	Night	10% 4 28% 36% 19% 3	1155

Page generated at 2026-08-27 02:07:09. Version ac07

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