Lucky Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lucky Lake clear sky chart from 2005-11-06 to 2025-02-25.

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	8% 8% 3 8% 5% 5% 5% 4 6% 8% 39%	111633
	Night	7% 8% 3 9% 6% 5% 5% 4 6% 8% 38%	115668
Transparency	Day	41% 7% 16% 25% 10% 1	111382
	Night	42% 6% 16% 24% 10% 1	115565
Seeing	Day	12% 9% 29% 29% 16% 4	16080
	Night	11% 8% 31% 34% 14% 1	25619

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	7% 12% 4 13% 8% 7% 6% 5% 6% 6% 27%	3179
	11th to 20th	Day	3 7% 4 11% 7% 8% 8% 6% 6% 7% 33%	3159
	21st to end	Day	4 10% 4 10% 6% 6% 5% 5% 7% 8% 34%	3838
February	1st to 10th	Day	6% 13% 5% 15% 7% 6% 6% 4 5% 7% 26%	1740
	11th to 20th	Day	7% 10% 5% 9% 8% 6% 5% 5% 6% 7% 31%	1755
	21st to end	Day	5% 9% 5% 12% 9% 7% 7% 5% 8% 7% 26%	1473
March	1st to 10th	Day	6% 13% 5% 11% 8% 7% 6% 4 5% 6% 29%	3149
	11th to 20th	Day	5% 11% 7% 13% 5% 4 4 3 5% 8% 36%	3489
	21st to end	Day	5% 10% 6% 14% 7% 6% 5% 4 7% 9% 27%	3979
April	1st to 10th	Day	7% 9% 4 9% 6% 6% 6% 4 7% 8% 35%	2280
	11th to 20th	Day	10% 14% 4 9% 6% 5% 5% 5% 6% 7% 29%	2343
	21st to end	Day	15% 10% 3 8% 5% 4 5% 4 5% 8% 34%	2603
May	1st to 10th	Day	22% 10% 2 5% 4 4 4 4 5% 7% 33%	4430
	11th to 20th	Day	7% 6% 3 8% 6% 6% 6% 6% 8% 9% 34%	4388
	21st to end	Day	14% 7% 3 8% 6% 6% 5% 4 7% 7% 32%	5028
June	1st to 10th	Day	14% 8% 3 5% 5% 4 5% 4 6% 8% 38%	2893
	11th to 20th	Day	17% 8% 2 6% 5% 5% 5% 4 7% 8% 32%	3040
	21st to end	Day	9% 5% 2 5% 4 5% 5% 5% 7% 11% 42%	2928
July	1st to 10th	Day	5% 4 2 7% 6% 5% 6% 5% 6% 9% 45%	4740
	11th to 20th	Day	7% 4 2 5% 3 4 5% 4 7% 9% 50%	4740
	21st to end	Day	4 2 1 3 3 3 4 3 5% 7% 64%	4968
August	1st to 10th	Day	7% 4 2 5% 4 4 5% 3 6% 8% 52%	4412
	11th to 20th	Day	6% 4 2 5% 4 5% 4 4 7% 9% 50%	4162
	21st to end	Day	10% 4 1 4 3 3 3 3 5% 7% 57%	4411
September	1st to 10th	Day	10% 5% 2 6% 4 5% 4 4 6% 7% 48%	2280
	11th to 20th	Day	13% 7% 2 6% 4 4 4 3 6% 6% 44%	2280
	21st to end	Day	11% 5% 2 5% 3 3 4 3 5% 8% 53%	2013
October	1st to 10th	Day	9% 5% 2 5% 3 4 4 3 6% 9% 50%	3170
	11th to 20th	Day	5% 6% 2 6% 4 4 4 4 7% 11% 47%	3150
	21st to end	Day	5% 7% 4 8% 5% 5% 6% 4 6% 8% 41%	3014
November	1st to 10th	Day	12% 14% 4 8% 6% 5% 4 3 4 7% 33%	1568
	11th to 20th	Day	6% 12% 4 13% 7% 5% 5% 4 7% 6% 30%	1600
	21st to end	Day	8% 13% 5% 12% 7% 5% 6% 4 6% 7% 28%	1600
December	1st to 10th	Day	5% 10% 4 11% 8% 8% 7% 5% 7% 7% 28%	2148
	11th to 20th	Day	7% 12% 4 15% 8% 9% 6% 4 5% 7% 24%	2259
	21st to end	Day	3 6% 3 8% 7% 6% 6% 4 6% 7% 43%	3424
January	1st to 10th	Night	2 10% 5% 12% 8% 7% 7% 5% 7% 7% 28%	6766
	11th to 20th	Night	4 8% 4 14% 8% 9% 8% 5% 7% 7% 26%	6739
	21st to end	Night	5% 9% 4 10% 6% 6% 6% 5% 7% 9% 33%	7131
February	1st to 10th	Night	6% 12% 4 11% 7% 6% 6% 5% 8% 8% 27%	2678
	11th to 20th	Night	5% 10% 4 12% 6% 6% 6% 5% 8% 7% 31%	2532
	21st to end	Night	3 9% 4 9% 7% 6% 6% 5% 7% 10% 32%	2075
March	1st to 10th	Night	6% 11% 5% 11% 7% 7% 6% 5% 7% 8% 28%	3713
	11th to 20th	Night	4 8% 4 10% 6% 6% 5% 4 6% 9% 38%	3490
	21st to end	Night	6% 8% 5% 14% 8% 6% 6% 5% 7% 8% 28%	3669
April	1st to 10th	Night	6% 8% 3 7% 5% 4 6% 5% 7% 9% 41%	1900
	11th to 20th	Night	10% 14% 4 9% 6% 5% 4 4 5% 6% 33%	1785
	21st to end	Night	13% 8% 3 9% 4 5% 5% 5% 6% 8% 34%	1577
May	1st to 10th	Night	22% 10% 3 6% 4 3 4 3 5% 6% 34%	2540
	11th to 20th	Night	11% 8% 3 6% 5% 4 6% 5% 5% 9% 38%	2518
	21st to end	Night	14% 7% 3 7% 4 5% 5% 4 7% 9% 38%	2549
June	1st to 10th	Night	11% 6% 2 6% 5% 4 4 3 5% 10% 42%	1283
	11th to 20th	Night	14% 5% 3 6% 5% 6% 6% 5% 7% 8% 35%	1140
	21st to end	Night	7% 4 1 4 4 4 5% 3 7% 11% 50%	1244
July	1st to 10th	Night	7% 3 1 6% 4 4 5% 4 6% 10% 49%	2220
	11th to 20th	Night	4 2 1 3 3 4 5% 3 6% 8% 60%	2220
	21st to end	Night	1 2 1 3 3 2 4 3 5% 7% 69%	2589
August	1st to 10th	Night	7% 4 2 4 3 3 4 4 5% 7% 57%	2528
	11th to 20th	Night	4 3 1 5% 4 4 5% 4 7% 8% 55%	2674
	21st to end	Night	8% 3 1 4 3 4 4 3 6% 8% 56%	3256
September	1st to 10th	Night	9% 3 1 5% 3 5% 4 4 5% 7% 53%	1900
	11th to 20th	Night	10% 7% 2 7% 4 3 4 3 6% 7% 48%	1900
	21st to end	Night	10% 5% 2 4 3 4 4 2 5% 8% 54%	2163
October	1st to 10th	Night	10% 6% 2 5% 4 4 4 3 5% 8% 48%	3800
	11th to 20th	Night	5% 5% 1 5% 3 4 4 3 6% 9% 54%	3778
	21st to end	Night	8% 7% 3 7% 5% 4 5% 4 5% 7% 44%	4508
November	1st to 10th	Night	13% 12% 4 8% 5% 5% 5% 4 5% 5% 33%	2730
	11th to 20th	Night	5% 10% 4 12% 7% 6% 6% 5% 6% 7% 32%	2800
	21st to end	Night	7% 13% 5% 11% 6% 5% 5% 4 6% 8% 31%	2800
December	1st to 10th	Night	8% 14% 5% 12% 9% 8% 5% 4 6% 7% 23%	5015
	11th to 20th	Night	6% 13% 5% 13% 9% 8% 6% 5% 6% 7% 23%	5933
	21st to end	Night	2 7% 3 10% 7% 6% 5% 3 5% 6% 47%	7525

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	56% 5% 13% 20% 6%	3179
	11th to 20th	Day	48% 7% 14% 20% 11% 1	3180
	21st to end	Day	44% 7% 25% 20% 4	3838
February	1st to 10th	Day	58% 5% 11% 18% 8%	1740
	11th to 20th	Day	51% 7% 14% 17% 11% 1	1764
	21st to end	Day	54% 5% 15% 17% 9%	1473
March	1st to 10th	Day	55% 5% 15% 18% 6%	3149
	11th to 20th	Day	46% 8% 19% 19% 8%	3490
	21st to end	Day	51% 8% 13% 21% 5%	3979
April	1st to 10th	Day	45% 8% 14% 20% 12%	2280
	11th to 20th	Day	52% 7% 14% 18% 8% 1	2343
	21st to end	Day	48% 6% 14% 22% 9% 1	2603
May	1st to 10th	Day	51% 5% 14% 23% 6% 1	4430
	11th to 20th	Day	39% 10% 13% 25% 13%	4392
	21st to end	Day	45% 11% 15% 21% 8%	5028
June	1st to 10th	Day	43% 7% 14% 24% 12% 1	2893
	11th to 20th	Day	48% 8% 13% 22% 8% 1	3040
	21st to end	Day	34% 9% 20% 28% 8% 1	2928
July	1st to 10th	Day	33% 10% 20% 24% 13% 1	4666
	11th to 20th	Day	29% 7% 15% 35% 13% 1	4659
	21st to end	Day	19% 4 14% 38% 20% 5%	4811
August	1st to 10th	Day	30% 7% 20% 30% 13% 1	4396
	11th to 20th	Day	28% 7% 16% 36% 13%	4204
	21st to end	Day	28% 4 16% 35% 16% 1	4410
September	1st to 10th	Day	34% 5% 15% 26% 16% 3	2280
	11th to 20th	Day	39% 6% 15% 26% 12% 2	2280
	21st to end	Day	32% 5% 14% 33% 14% 2	2013
October	1st to 10th	Day	31% 5% 17% 35% 10% 2	3170
	11th to 20th	Day	30% 4 15% 40% 10% 1	3150
	21st to end	Day	40% 5% 16% 32% 6%	3014
November	1st to 10th	Day	53% 6% 14% 19% 8% 1	1568
	11th to 20th	Day	53% 6% 15% 20% 5% 1	1600
	21st to end	Day	54% 7% 18% 18% 4	1600
December	1st to 10th	Day	51% 12% 18% 12% 7%	2148
	11th to 20th	Day	60% 5% 21% 9% 5%	2260
	21st to end	Day	38% 5% 12% 24% 15% 6%	3424
January	1st to 10th	Night	51% 7% 15% 20% 6%	6766
	11th to 20th	Night	54% 5% 14% 14% 12% 1	6780
	21st to end	Night	44% 8% 21% 23% 3	7131
February	1st to 10th	Night	52% 6% 15% 17% 9%	2678
	11th to 20th	Night	49% 6% 14% 18% 13% 1	2533
	21st to end	Night	45% 6% 16% 23% 10%	2075
March	1st to 10th	Night	50% 6% 17% 21% 5%	3713
	11th to 20th	Night	42% 7% 21% 22% 7%	3490
	21st to end	Night	50% 8% 14% 20% 7%	3669
April	1st to 10th	Night	37% 8% 16% 23% 15% 1	1900
	11th to 20th	Night	51% 6% 11% 19% 11% 3	1785
	21st to end	Night	47% 7% 12% 23% 11% 1	1577
May	1st to 10th	Night	50% 6% 12% 23% 9%	2540
	11th to 20th	Night	40% 9% 11% 22% 16% 2	2518
	21st to end	Night	41% 7% 15% 28% 9%	2549
June	1st to 10th	Night	38% 5% 16% 27% 13% 1	1283
	11th to 20th	Night	44% 9% 13% 21% 13% 1	1140
	21st to end	Night	29% 8% 20% 31% 12% 1	1244
July	1st to 10th	Night	29% 8% 23% 30% 10%	2185
	11th to 20th	Night	20% 6% 14% 41% 17% 1	2178
	21st to end	Night	14% 4 14% 45% 20% 3	2507
August	1st to 10th	Night	26% 5% 19% 33% 15% 2	2520
	11th to 20th	Night	25% 7% 15% 36% 16% 1	2698
	21st to end	Night	26% 6% 11% 36% 19% 2	3256
September	1st to 10th	Night	29% 6% 13% 28% 17% 7%	1900
	11th to 20th	Night	35% 7% 13% 29% 13% 3	1900
	21st to end	Night	29% 6% 11% 33% 18% 3	2163
October	1st to 10th	Night	36% 4 17% 30% 14%	3800
	11th to 20th	Night	28% 4 16% 38% 14% 1	3778
	21st to end	Night	39% 5% 11% 35% 9% 1	4508
November	1st to 10th	Night	52% 7% 13% 19% 8% 1	2730
	11th to 20th	Night	49% 8% 18% 18% 6% 1	2800
	21st to end	Night	50% 7% 18% 21% 4	2800
December	1st to 10th	Night	60% 6% 18% 12% 4	5015
	11th to 20th	Night	59% 7% 20% 12% 3	5931
	21st to end	Night	38% 5% 11% 27% 15% 4	7525

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	10% 13% 24% 29% 20% 5%	200
	11th to 20th	Day	8% 11% 33% 30% 18%	200
	21st to end	Day	8% 15% 32% 31% 13%	293
February	1st to 10th	Day	12% 14% 36% 28% 8% 3	300
	11th to 20th	Day	8% 9% 31% 34% 13% 6%	300
	21st to end	Day	5% 9% 36% 32% 12% 6%	237
March	1st to 10th	Day	10% 13% 34% 26% 13% 4	276
	11th to 20th	Day	11% 11% 34% 28% 12% 4	460
	21st to end	Day	12% 9% 32% 26% 17% 4	506
April	1st to 10th	Day	9% 16% 34% 28% 11% 2	460
	11th to 20th	Day	15% 16% 33% 26% 8% 2	452
	21st to end	Day	18% 10% 31% 29% 12% 1	593
May	1st to 10th	Day	16% 7% 25% 29% 19% 4	653
	11th to 20th	Day	9% 9% 25% 34% 17% 6%	675
	21st to end	Day	15% 10% 22% 26% 22% 6%	734
June	1st to 10th	Day	14% 10% 30% 27% 14% 4	680
	11th to 20th	Day	19% 14% 29% 23% 11% 3	680
	21st to end	Day	10% 9% 23% 33% 20% 5%	680
July	1st to 10th	Day	7% 5% 24% 35% 23% 6%	671
	11th to 20th	Day	10% 6% 25% 32% 20% 6%	668
	21st to end	Day	6% 7% 23% 27% 28% 9%	739
August	1st to 10th	Day	9% 4 22% 35% 22% 7%	676
	11th to 20th	Day	10% 6% 22% 34% 21% 8%	562
	21st to end	Day	11% 7% 25% 34% 18% 6%	539
September	1st to 10th	Day	11% 9% 28% 30% 18% 4	490
	11th to 20th	Day	16% 9% 28% 30% 16% 2	490
	21st to end	Day	15% 8% 34% 26% 14% 4	369
October	1st to 10th	Day	18% 5% 28% 25% 18% 5%	300
	11th to 20th	Day	6% 12% 36% 26% 15% 5%	300
	21st to end	Day	9% 12% 43% 24% 10% 2	330
November	1st to 10th	Day	20% 10% 34% 25% 9% 2	300
	11th to 20th	Day	13% 15% 35% 27% 9% 1	300
	21st to end	Day	7% 12% 40% 26% 13% 3	300
December	1st to 10th	Day	9% 7% 45% 27% 9% 4	247
	11th to 20th	Day	8% 12% 43% 28% 9% 2	200
	21st to end	Day	12% 5% 35% 27% 18% 4	220
January	1st to 10th	Night	7% 11% 35% 35% 11% 1	1000
	11th to 20th	Night	8% 14% 39% 30% 9% 1	1000
	21st to end	Night	10% 12% 40% 28% 10% 1	1100
February	1st to 10th	Night	11% 8% 31% 37% 12% 1	878
	11th to 20th	Night	10% 8% 34% 36% 11% 2	784
	21st to end	Night	6% 7% 25% 38% 20% 4	646
March	1st to 10th	Night	10% 8% 33% 34% 14% 1	760
	11th to 20th	Night	9% 7% 34% 35% 12% 2	760
	21st to end	Night	11% 6% 30% 36% 15% 2	741
April	1st to 10th	Night	10% 9% 29% 40% 11% 1	570
	11th to 20th	Night	15% 10% 34% 33% 8% 1	563
	21st to end	Night	16% 8% 33% 31% 12%	570
May	1st to 10th	Night	14% 7% 26% 34% 18% 1	570
	11th to 20th	Night	12% 6% 28% 34% 18% 2	561
	21st to end	Night	19% 5% 21% 33% 18% 4	495
June	1st to 10th	Night	13% 8% 28% 33% 15% 2	380
	11th to 20th	Night	14% 10% 24% 34% 17%	380
	21st to end	Night	6% 7% 24% 40% 21% 2	380
July	1st to 10th	Night	8% 5% 16% 48% 24% 1	370
	11th to 20th	Night	6% 5% 26% 43% 18% 2	368
	21st to end	Night	3 4 25% 43% 22% 2	516
August	1st to 10th	Night	6% 5% 24% 41% 21% 3	567
	11th to 20th	Night	5% 4 18% 41% 29% 2	564
	21st to end	Night	8% 4 25% 39% 22% 2	627
September	1st to 10th	Night	10% 4 28% 39% 18% 2	570
	11th to 20th	Night	12% 6% 20% 44% 16% 1	570
	21st to end	Night	11% 6% 31% 36% 14% 1	712
October	1st to 10th	Night	16% 6% 28% 33% 15%	760
	11th to 20th	Night	9% 9% 33% 33% 14% 1	760
	21st to end	Night	12% 13% 36% 30% 9%	1022
November	1st to 10th	Night	19% 9% 33% 30% 8% 1	975
	11th to 20th	Night	9% 13% 35% 32% 10% 2	1000
	21st to end	Night	12% 12% 39% 30% 7% 1	1000
December	1st to 10th	Night	11% 10% 36% 29% 13% 2	1000
	11th to 20th	Night	11% 11% 38% 29% 11% 1	1000
	21st to end	Night	9% 9% 32% 33% 14% 3	1100

Page generated at 2025-02-22 05:51:33. Version ac07

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