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 2024-10-25.

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 6% 8% 35%	101904
	Night	9% 10% 4 10% 6% 6% 5% 4 6% 8% 33%	96966
Transparency	Day	46% 8% 17% 22% 7%	101646
	Night	48% 8% 16% 21% 7% 1	96870
Seeing	Day	13% 8% 28% 30% 16% 4	15606
	Night	13% 6% 29% 35% 15% 2	24583

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	5% 15% 6% 18% 10% 7% 5% 3 5% 5% 20%	2219
	11th to 20th	Day	5% 9% 4 11% 6% 7% 11% 7% 8% 10% 23%	2199
	21st to end	Day	6% 14% 6% 15% 8% 6% 4 4 5% 5% 28%	2442
February	1st to 10th	Day	7% 13% 4 11% 8% 7% 6% 5% 7% 6% 25%	1509
	11th to 20th	Day	6% 10% 5% 13% 8% 7% 6% 5% 7% 8% 26%	1665
	21st to end	Day	6% 11% 4 13% 9% 8% 6% 4 8% 8% 25%	1413
March	1st to 10th	Day	4 9% 4 10% 6% 6% 7% 6% 8% 10% 30%	3126
	11th to 20th	Day	5% 9% 4 8% 6% 6% 6% 4 8% 10% 35%	3489
	21st to end	Day	9% 12% 4 11% 6% 5% 6% 3 5% 7% 32%	3853
April	1st to 10th	Day	8% 12% 4 8% 6% 6% 5% 5% 7% 8% 32%	2375
	11th to 20th	Day	12% 11% 3 8% 6% 6% 6% 4 6% 7% 31%	2440
	21st to end	Day	12% 11% 3 9% 5% 6% 5% 4 6% 7% 32%	2578
May	1st to 10th	Day	14% 11% 4 9% 6% 5% 5% 4 6% 6% 30%	4523
	11th to 20th	Day	15% 10% 3 9% 5% 5% 5% 4 6% 6% 32%	4694
	21st to end	Day	12% 8% 3 9% 5% 6% 6% 5% 8% 9% 30%	5220
June	1st to 10th	Day	17% 6% 3 8% 5% 5% 6% 5% 6% 8% 30%	3040
	11th to 20th	Day	20% 9% 3 8% 5% 6% 5% 4 8% 7% 25%	3040
	21st to end	Day	12% 8% 3 8% 5% 6% 6% 4 7% 8% 33%	3040
July	1st to 10th	Day	8% 5% 2 5% 4 5% 6% 4 7% 10% 45%	4908
	11th to 20th	Day	8% 4 2 5% 3 5% 5% 5% 7% 11% 46%	4740
	21st to end	Day	13% 5% 2 5% 4 5% 5% 5% 7% 8% 42%	5138
August	1st to 10th	Day	11% 6% 3 6% 4 4 4 3 5% 7% 46%	4699
	11th to 20th	Day	9% 5% 2 7% 5% 5% 5% 5% 7% 9% 42%	4129
	21st to end	Day	9% 5% 2 6% 4 4 4 4 7% 8% 46%	4521
September	1st to 10th	Day	13% 7% 2 7% 4 4 4 4 5% 8% 42%	2366
	11th to 20th	Day	17% 8% 2 6% 4 3 4 3 5% 8% 40%	2197
	21st to end	Day	9% 7% 2 7% 5% 4 5% 4 7% 8% 41%	2060
October	1st to 10th	Day	13% 11% 3 7% 6% 4 4 4 6% 7% 35%	1900
	11th to 20th	Day	11% 9% 4 7% 5% 5% 5% 4 6% 7% 37%	1855
	21st to end	Day	10% 14% 5% 10% 5% 5% 5% 4 6% 7% 30%	1663
November	1st to 10th	Day	11% 15% 4 12% 7% 6% 5% 3 5% 7% 24%	1488
	11th to 20th	Day	9% 14% 5% 14% 7% 5% 6% 4 7% 6% 22%	1459
	21st to end	Day	6% 12% 5% 14% 7% 7% 6% 4 6% 7% 28%	1238
December	1st to 10th	Day	6% 10% 5% 14% 11% 6% 6% 4 6% 8% 24%	1140
	11th to 20th	Day	8% 13% 5% 14% 7% 6% 5% 5% 6% 8% 24%	1439
	21st to end	Day	4 9% 3 9% 5% 6% 6% 5% 7% 7% 40%	2099
January	1st to 10th	Night	5% 12% 6% 19% 10% 8% 5% 3 6% 6% 19%	4726
	11th to 20th	Night	4 9% 3 11% 8% 10% 10% 6% 7% 9% 23%	4699
	21st to end	Night	6% 12% 6% 13% 8% 6% 5% 4 6% 7% 28%	5214
February	1st to 10th	Night	7% 12% 4 12% 8% 7% 6% 5% 6% 7% 26%	2690
	11th to 20th	Night	6% 11% 4 10% 7% 6% 5% 4 6% 7% 31%	2402
	21st to end	Night	3 10% 5% 10% 7% 7% 8% 6% 6% 7% 29%	2041
March	1st to 10th	Night	5% 12% 5% 12% 7% 6% 5% 5% 6% 10% 27%	3744
	11th to 20th	Night	6% 9% 3 7% 6% 6% 8% 6% 7% 9% 34%	3490
	21st to end	Night	8% 14% 4 10% 6% 5% 5% 4 6% 7% 30%	3799
April	1st to 10th	Night	7% 10% 3 9% 5% 6% 5% 5% 7% 9% 35%	1802
	11th to 20th	Night	10% 9% 3 9% 6% 5% 5% 4 8% 7% 33%	1691
	21st to end	Night	13% 10% 4 8% 5% 4 3 4 5% 7% 36%	1601
May	1st to 10th	Night	15% 12% 4 8% 6% 4 4 4 6% 8% 30%	2429
	11th to 20th	Night	17% 7% 3 8% 5% 4 4 5% 5% 6% 36%	2199
	21st to end	Night	14% 10% 3 8% 6% 6% 5% 5% 7% 8% 29%	2354
June	1st to 10th	Night	17% 7% 4 7% 5% 4 5% 4 6% 7% 33%	1140
	11th to 20th	Night	17% 10% 2 8% 6% 6% 6% 4 7% 9% 24%	1140
	21st to end	Night	13% 5% 2 6% 5% 5% 6% 5% 7% 9% 39%	1140
July	1st to 10th	Night	8% 4 2 5% 3 4 4 4 9% 9% 49%	2049
	11th to 20th	Night	6% 4 1 4 4 4 5% 4 7% 9% 52%	2220
	21st to end	Night	15% 5% 2 5% 3 3 4 3 6% 8% 45%	2414
August	1st to 10th	Night	12% 6% 3 6% 4 4 5% 4 7% 7% 44%	2232
	11th to 20th	Night	7% 4 2 7% 5% 5% 6% 5% 8% 10% 41%	2709
	21st to end	Night	8% 5% 2 6% 5% 4 5% 4 6% 7% 47%	3146
September	1st to 10th	Night	14% 6% 2 6% 3 4 4 4 6% 7% 44%	1814
	11th to 20th	Night	12% 7% 2 6% 5% 4 4 4 6% 8% 44%	1981
	21st to end	Night	8% 6% 2 5% 4 4 6% 4 7% 9% 45%	2119
October	1st to 10th	Night	12% 8% 3 8% 5% 5% 5% 4 6% 7% 38%	2280
	11th to 20th	Night	10% 10% 3 7% 6% 4 5% 4 7% 7% 37%	2323
	21st to end	Night	12% 13% 4 9% 6% 5% 5% 4 5% 6% 30%	2780
November	1st to 10th	Night	12% 16% 6% 9% 7% 5% 5% 4 5% 6% 25%	2590
	11th to 20th	Night	10% 13% 5% 14% 7% 6% 5% 4 7% 6% 23%	2720
	21st to end	Night	6% 13% 6% 13% 7% 6% 4 4 7% 7% 26%	2940
December	1st to 10th	Night	8% 12% 4 11% 7% 8% 5% 5% 7% 7% 25%	3040
	11th to 20th	Night	8% 14% 5% 15% 8% 6% 6% 4 6% 7% 20%	3753
	21st to end	Night	4 8% 4 9% 6% 5% 5% 5% 6% 6% 43%	5555

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	66% 6% 12% 12% 4	2219
	11th to 20th	Day	53% 9% 15% 17% 6% 1	2220
	21st to end	Day	57% 8% 16% 13% 6%	2442
February	1st to 10th	Day	56% 9% 13% 13% 10%	1509
	11th to 20th	Day	53% 7% 15% 17% 7% 1	1674
	21st to end	Day	55% 6% 15% 17% 7%	1413
March	1st to 10th	Day	44% 8% 21% 23% 5%	3126
	11th to 20th	Day	42% 9% 19% 24% 6%	3490
	21st to end	Day	49% 7% 13% 20% 12%	3853
April	1st to 10th	Day	48% 8% 16% 19% 9%	2375
	11th to 20th	Day	52% 6% 12% 19% 9% 1	2440
	21st to end	Day	50% 7% 13% 21% 8% 1	2578
May	1st to 10th	Day	51% 8% 12% 19% 9% 1	4523
	11th to 20th	Day	49% 8% 11% 20% 11% 1	4698
	21st to end	Day	46% 11% 16% 19% 8%	5221
June	1st to 10th	Day	48% 10% 15% 17% 9% 1	3040
	11th to 20th	Day	55% 9% 13% 18% 4 1	3040
	21st to end	Day	46% 10% 15% 22% 6% 1	3040
July	1st to 10th	Day	32% 9% 28% 26% 5%	4833
	11th to 20th	Day	31% 8% 19% 31% 11%	4659
	21st to end	Day	37% 10% 22% 28% 3	4976
August	1st to 10th	Day	37% 8% 21% 32% 2	4681
	11th to 20th	Day	36% 9% 25% 24% 5%	4171
	21st to end	Day	35% 7% 27% 28% 3	4520
September	1st to 10th	Day	40% 9% 17% 26% 8% 1	2366
	11th to 20th	Day	43% 7% 21% 25% 4	2197
	21st to end	Day	39% 8% 18% 23% 9% 1	2060
October	1st to 10th	Day	47% 8% 17% 23% 5%	1900
	11th to 20th	Day	46% 7% 15% 26% 6%	1855
	21st to end	Day	55% 8% 16% 16% 5%	1663
November	1st to 10th	Day	62% 9% 12% 13% 4	1488
	11th to 20th	Day	63% 8% 14% 12% 3	1459
	21st to end	Day	58% 8% 13% 16% 4 1	1238
December	1st to 10th	Day	60% 7% 11% 16% 5% 1	1140
	11th to 20th	Day	60% 8% 13% 15% 4	1440
	21st to end	Day	40% 6% 16% 26% 11% 1	2099
January	1st to 10th	Night	64% 7% 11% 12% 6%	4726
	11th to 20th	Night	55% 7% 16% 16% 5% 1	4740
	21st to end	Night	55% 9% 17% 14% 5%	5214
February	1st to 10th	Night	55% 8% 12% 17% 8%	2690
	11th to 20th	Night	50% 6% 13% 21% 9%	2403
	21st to end	Night	50% 8% 14% 18% 10%	2041
March	1st to 10th	Night	50% 7% 17% 21% 5%	3744
	11th to 20th	Night	41% 11% 19% 23% 5%	3490
	21st to end	Night	49% 6% 12% 20% 12%	3799
April	1st to 10th	Night	45% 7% 14% 20% 14%	1802
	11th to 20th	Night	47% 8% 11% 19% 13% 3	1691
	21st to end	Night	47% 7% 12% 20% 12% 2	1601
May	1st to 10th	Night	51% 6% 8% 24% 9% 1	2429
	11th to 20th	Night	45% 8% 10% 25% 12% 1	2199
	21st to end	Night	46% 12% 17% 17% 6% 1	2354
June	1st to 10th	Night	48% 8% 13% 18% 11% 2	1140
	11th to 20th	Night	52% 11% 14% 15% 7% 1	1140
	21st to end	Night	40% 9% 17% 22% 11% 1	1140
July	1st to 10th	Night	28% 9% 26% 28% 8% 1	2015
	11th to 20th	Night	27% 7% 16% 38% 11%	2178
	21st to end	Night	37% 7% 24% 26% 6%	2337
August	1st to 10th	Night	36% 7% 19% 36% 2	2225
	11th to 20th	Night	35% 9% 28% 22% 6%	2733
	21st to end	Night	36% 6% 23% 32% 4	3146
September	1st to 10th	Night	39% 6% 20% 25% 8% 2	1814
	11th to 20th	Night	40% 7% 19% 26% 8%	1981
	21st to end	Night	34% 8% 17% 29% 10% 2	2119
October	1st to 10th	Night	46% 6% 16% 24% 8%	2280
	11th to 20th	Night	45% 7% 15% 25% 7%	2323
	21st to end	Night	55% 7% 13% 17% 7%	2780
November	1st to 10th	Night	61% 8% 10% 16% 5%	2590
	11th to 20th	Night	62% 9% 14% 11% 4	2720
	21st to end	Night	57% 8% 16% 15% 4	2940
December	1st to 10th	Night	57% 7% 13% 16% 6% 1	3040
	11th to 20th	Night	62% 8% 14% 11% 5%	3751
	21st to end	Night	39% 7% 15% 25% 13% 2	5555

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% 36% 17% 6%	180
	11th to 20th	Day	14% 8% 25% 36% 12% 6%	180
	21st to end	Day	9% 12% 31% 37% 8% 4	198
February	1st to 10th	Day	10% 7% 39% 33% 10% 2	200
	11th to 20th	Day	8% 9% 31% 30% 19% 5%	270
	21st to end	Day	7% 8% 31% 35% 16% 4	225
March	1st to 10th	Day	10% 8% 34% 34% 13% 1	370
	11th to 20th	Day	9% 11% 38% 27% 11% 3	460
	21st to end	Day	15% 7% 33% 32% 11% 2	506
April	1st to 10th	Day	10% 12% 37% 30% 10% 2	460
	11th to 20th	Day	18% 11% 31% 26% 12% 3	452
	21st to end	Day	13% 11% 34% 30% 10% 2	568
May	1st to 10th	Day	11% 11% 28% 29% 17% 5%	653
	11th to 20th	Day	10% 8% 26% 31% 18% 7%	675
	21st to end	Day	16% 7% 23% 29% 19% 5%	734
June	1st to 10th	Day	19% 10% 29% 28% 12% 3	680
	11th to 20th	Day	20% 10% 26% 25% 15% 5%	680
	21st to end	Day	11% 5% 21% 32% 22% 9%	680
July	1st to 10th	Day	12% 5% 22% 31% 25% 6%	671
	11th to 20th	Day	10% 5% 23% 33% 23% 6%	668
	21st to end	Day	9% 5% 26% 29% 22% 8%	739
August	1st to 10th	Day	13% 5% 18% 29% 26% 8%	676
	11th to 20th	Day	10% 6% 23% 36% 21% 4	542
	21st to end	Day	10% 8% 24% 31% 21% 6%	539
September	1st to 10th	Day	14% 11% 29% 27% 16% 3	490
	11th to 20th	Day	21% 7% 23% 30% 17% 3	490
	21st to end	Day	11% 13% 32% 28% 12% 3	460
October	1st to 10th	Day	13% 9% 29% 32% 14% 3	300
	11th to 20th	Day	18% 9% 35% 27% 11%	300
	21st to end	Day	18% 14% 28% 26% 11% 2	311
November	1st to 10th	Day	18% 11% 23% 32% 14% 1	270
	11th to 20th	Day	15% 10% 44% 25% 4 2	241
	21st to end	Day	9% 11% 36% 32% 6% 6%	180
December	1st to 10th	Day	7% 7% 34% 33% 17% 3	180
	11th to 20th	Day	10% 8% 41% 31% 9% 1	180
	21st to end	Day	7% 6% 29% 34% 19% 6%	198
January	1st to 10th	Night	12% 6% 29% 37% 14% 2	950
	11th to 20th	Night	11% 5% 31% 39% 12% 2	950
	21st to end	Night	14% 9% 34% 32% 9% 2	1045
February	1st to 10th	Night	11% 7% 26% 39% 16% 2	832
	11th to 20th	Night	11% 4 33% 35% 15% 2	744
	21st to end	Night	7% 4 24% 42% 20% 3	628
March	1st to 10th	Night	10% 4 31% 39% 13% 2	760
	11th to 20th	Night	12% 6% 32% 36% 12% 2	760
	21st to end	Night	13% 8% 25% 35% 15% 2	819
April	1st to 10th	Night	9% 5% 32% 38% 14% 1	570
	11th to 20th	Night	13% 8% 30% 33% 14% 2	563
	21st to end	Night	17% 7% 28% 33% 14% 1	570
May	1st to 10th	Night	14% 9% 26% 33% 16% 1	511
	11th to 20th	Night	12% 4 28% 38% 15% 3	374
	21st to end	Night	16% 5% 23% 34% 19% 3	411
June	1st to 10th	Night	18% 7% 23% 32% 18% 1	380
	11th to 20th	Night	20% 6% 22% 30% 20% 2	380
	21st to end	Night	13% 2 19% 34% 28% 4	380
July	1st to 10th	Night	11% 3 20% 36% 29% 1	370
	11th to 20th	Night	12% 2 19% 40% 25% 2	368
	21st to end	Night	10% 3 19% 41% 22% 6%	416
August	1st to 10th	Night	11% 1 17% 37% 27% 6%	387
	11th to 20th	Night	9% 3 19% 40% 27% 2	564
	21st to end	Night	11% 4 24% 39% 21% 2	627
September	1st to 10th	Night	18% 3 25% 32% 21% 1	570
	11th to 20th	Night	13% 6% 24% 38% 19% 1	651
	21st to end	Night	10% 6% 32% 36% 14% 1	760
October	1st to 10th	Night	16% 6% 31% 35% 10% 2	760
	11th to 20th	Night	15% 6% 32% 33% 13% 2	760
	21st to end	Night	17% 10% 33% 29% 10% 1	953
November	1st to 10th	Night	18% 7% 31% 32% 10% 2	925
	11th to 20th	Night	16% 7% 32% 32% 11% 3	950
	21st to end	Night	12% 6% 40% 32% 8% 1	950
December	1st to 10th	Night	13% 6% 33% 30% 15% 3	950
	11th to 20th	Night	12% 7% 33% 36% 9% 2	950
	21st to end	Night	9% 4 29% 37% 18% 3	1045

Page generated at 2024-10-22 18:21:03. Version ac07

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