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 2026-07-01.

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% 7% 3 8% 5% 5% 5% 4 6% 8% 39%	141313
	Night	7% 8% 3 9% 6% 5% 5% 4 6% 8% 38%	139725
Transparency	Day	41% 6% 15% 26% 11% 1	141019
	Night	43% 6% 15% 24% 11% 1	139605
Seeing	Day	12% 10% 29% 29% 16% 4	17995
	Night	11% 9% 31% 34% 14% 1	27311

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% 11% 4 12% 8% 8% 6% 5% 6% 7% 27%	4125
	11th to 20th	Day	2 6% 3 11% 7% 9% 9% 6% 6% 8% 32%	4119
	21st to end	Day	3 10% 4 11% 7% 7% 6% 5% 7% 8% 32%	4980
February	1st to 10th	Day	6% 13% 5% 15% 7% 6% 6% 4 5% 7% 27%	1827
	11th to 20th	Day	7% 10% 5% 9% 8% 6% 5% 4 6% 7% 32%	1845
	21st to end	Day	5% 9% 5% 12% 9% 8% 7% 5% 8% 7% 26%	1583
March	1st to 10th	Day	6% 11% 4 13% 6% 5% 5% 3 5% 8% 34%	4619
	11th to 20th	Day	4 11% 8% 18% 7% 5% 4 3 5% 7% 29%	5109
	21st to end	Day	6% 12% 7% 14% 6% 5% 5% 3 6% 8% 27%	5831
April	1st to 10th	Day	7% 10% 4 9% 6% 6% 6% 4 7% 8% 34%	2520
	11th to 20th	Day	10% 13% 4 9% 6% 5% 5% 5% 6% 7% 30%	2593
	21st to end	Day	15% 11% 3 8% 4 4 4 4 5% 8% 35%	2877
May	1st to 10th	Day	13% 7% 2 5% 4 5% 5% 4 5% 7% 42%	8224
	11th to 20th	Day	13% 8% 3 8% 5% 6% 6% 5% 7% 9% 30%	8191
	21st to end	Day	10% 5% 2 6% 5% 5% 5% 4 6% 8% 43%	9399
June	1st to 10th	Day	14% 8% 3 6% 5% 4 5% 4 7% 8% 37%	3197
	11th to 20th	Day	17% 8% 2 6% 5% 5% 6% 5% 7% 8% 32%	3360
	21st to end	Day	11% 5% 2 5% 5% 5% 5% 5% 7% 11% 40%	3236
July	1st to 10th	Day	6% 4 2 7% 5% 5% 5% 4 6% 8% 48%	6781
	11th to 20th	Day	9% 5% 2 6% 4 5% 5% 5% 7% 9% 44%	6780
	21st to end	Day	7% 3 1 4 3 3 4 3 5% 7% 59%	7129
August	1st to 10th	Day	8% 4 2 5% 4 4 5% 3 6% 8% 51%	4552
	11th to 20th	Day	6% 4 2 5% 4 5% 5% 4 8% 9% 50%	4296
	21st to end	Day	10% 4 2 4 3 3 3 3 5% 6% 57%	4551
September	1st to 10th	Day	9% 5% 2 6% 4 5% 4 4 6% 7% 49%	2400
	11th to 20th	Day	13% 7% 2 6% 4 4 4 4 6% 6% 44%	2400
	21st to end	Day	10% 5% 1 5% 2 3 4 3 5% 8% 54%	2118
October	1st to 10th	Day	9% 5% 2 5% 3 4 4 3 6% 9% 50%	3270
	11th to 20th	Day	5% 6% 2 6% 4 4 4 4 7% 11% 46%	3250
	21st to end	Day	5% 7% 4 8% 5% 5% 6% 4 6% 8% 41%	3110
November	1st to 10th	Day	12% 14% 4 8% 6% 5% 5% 3 4 6% 33%	1648
	11th to 20th	Day	6% 12% 4 13% 7% 5% 6% 4 6% 7% 30%	1680
	21st to end	Day	8% 13% 5% 11% 7% 5% 6% 4 6% 7% 28%	1680
December	1st to 10th	Day	5% 10% 4 11% 8% 8% 7% 5% 7% 7% 27%	2214
	11th to 20th	Day	7% 12% 4 15% 8% 9% 6% 4 5% 7% 24%	2319
	21st to end	Day	3 7% 3 9% 6% 6% 6% 4 6% 7% 42%	3500
January	1st to 10th	Night	3 11% 5% 13% 8% 7% 7% 5% 7% 8% 28%	8768
	11th to 20th	Night	3 7% 4 13% 8% 8% 8% 5% 8% 8% 29%	8779
	21st to end	Night	4 9% 4 11% 6% 6% 7% 5% 8% 9% 31%	9222
February	1st to 10th	Night	6% 12% 4 11% 7% 6% 6% 5% 7% 8% 27%	2812
	11th to 20th	Night	5% 10% 4 12% 6% 6% 5% 5% 7% 7% 31%	2662
	21st to end	Night	3 8% 5% 10% 7% 6% 6% 5% 7% 10% 32%	2222
March	1st to 10th	Night	5% 9% 4 11% 6% 6% 6% 5% 6% 9% 33%	5460
	11th to 20th	Night	5% 10% 4 11% 7% 6% 6% 4 5% 8% 33%	5110
	21st to end	Night	9% 12% 5% 13% 7% 5% 6% 4 6% 7% 26%	5376
April	1st to 10th	Night	6% 9% 3 7% 4 4 6% 5% 7% 9% 40%	2100
	11th to 20th	Night	10% 13% 4 9% 5% 4 4 4 6% 6% 33%	1975
	21st to end	Night	13% 8% 3 9% 4 5% 5% 5% 6% 8% 34%	1743
May	1st to 10th	Night	13% 7% 2 6% 4 4 4 3 5% 6% 46%	4724
	11th to 20th	Night	16% 10% 3 7% 5% 4 6% 4 5% 8% 30%	4702
	21st to end	Night	11% 6% 3 6% 4 4 4 4 6% 9% 44%	4769
June	1st to 10th	Night	11% 6% 2 6% 5% 4 4 3 5% 10% 42%	1418
	11th to 20th	Night	13% 6% 3 7% 5% 6% 6% 5% 8% 8% 34%	1260
	21st to end	Night	9% 4 1 5% 4 4 5% 3 6% 10% 49%	1376
July	1st to 10th	Night	7% 3 1 5% 4 4 5% 4 6% 9% 50%	3180
	11th to 20th	Night	5% 4 2 5% 4 4 6% 4 7% 8% 51%	3180
	21st to end	Night	6% 3 1 3 3 3 3 3 5% 8% 61%	3711
August	1st to 10th	Night	7% 4 2 5% 3 3 4 4 5% 7% 56%	2608
	11th to 20th	Night	4 3 1 5% 4 4 5% 4 8% 8% 55%	2759
	21st to end	Night	8% 3 1 4 3 3 4 3 6% 8% 56%	3358
September	1st to 10th	Night	9% 3 1 5% 3 5% 4 4 5% 7% 54%	2000
	11th to 20th	Night	10% 7% 2 7% 4 3 4 3 6% 8% 48%	2000
	21st to end	Night	9% 4 2 4 3 3 4 2 5% 7% 56%	2278
October	1st to 10th	Night	10% 6% 2 5% 4 4 4 3 5% 8% 48%	3920
	11th to 20th	Night	5% 5% 1 5% 4 4 4 3 6% 9% 54%	3898
	21st to end	Night	8% 7% 3 7% 5% 4 5% 4 5% 7% 45%	4652
November	1st to 10th	Night	13% 12% 4 8% 5% 5% 5% 4 5% 5% 33%	2870
	11th to 20th	Night	5% 10% 4 12% 6% 6% 6% 5% 6% 7% 33%	2940
	21st to end	Night	7% 13% 5% 11% 6% 5% 5% 4 6% 8% 31%	2940
December	1st to 10th	Night	8% 14% 5% 12% 9% 8% 5% 4 6% 7% 23%	5169
	11th to 20th	Night	6% 13% 5% 12% 9% 8% 6% 5% 7% 8% 22%	6093
	21st to end	Night	3 7% 3 10% 7% 6% 5% 3 5% 6% 46%	7691

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	55% 5% 13% 20% 8%	4125
	11th to 20th	Day	47% 7% 14% 20% 11% 1	4140
	21st to end	Day	46% 7% 21% 19% 6%	4980
February	1st to 10th	Day	57% 5% 11% 19% 8%	1827
	11th to 20th	Day	50% 6% 14% 18% 11% 1	1854
	21st to end	Day	54% 5% 15% 18% 8%	1583
March	1st to 10th	Day	49% 5% 19% 20% 7%	4619
	11th to 20th	Day	55% 6% 15% 18% 6%	5110
	21st to end	Day	54% 7% 11% 22% 5%	5831
April	1st to 10th	Day	45% 8% 14% 21% 12%	2520
	11th to 20th	Day	51% 7% 14% 18% 8% 1	2593
	21st to end	Day	47% 6% 13% 24% 9% 1	2877
May	1st to 10th	Day	41% 4 10% 28% 16% 2	8224
	11th to 20th	Day	47% 8% 11% 22% 12%	8195
	21st to end	Day	35% 8% 12% 30% 14% 1	9399
June	1st to 10th	Day	43% 7% 13% 24% 12% 1	3197
	11th to 20th	Day	48% 8% 13% 22% 8% 1	3360
	21st to end	Day	36% 9% 20% 27% 8% 1	3236
July	1st to 10th	Day	32% 8% 20% 25% 14% 1	6707
	11th to 20th	Day	35% 7% 15% 33% 9% 1	6699
	21st to end	Day	24% 5% 17% 34% 15% 4	6929
August	1st to 10th	Day	30% 7% 20% 30% 13% 1	4536
	11th to 20th	Day	28% 7% 16% 36% 13%	4338
	21st to end	Day	27% 4 16% 35% 16% 1	4550
September	1st to 10th	Day	34% 6% 14% 27% 16% 3	2400
	11th to 20th	Day	38% 6% 15% 27% 12% 2	2400
	21st to end	Day	30% 5% 14% 34% 15% 2	2118
October	1st to 10th	Day	31% 5% 16% 36% 10% 2	3270
	11th to 20th	Day	31% 4 15% 39% 10% 1	3250
	21st to end	Day	40% 5% 16% 32% 7%	3110
November	1st to 10th	Day	53% 6% 14% 19% 8% 1	1648
	11th to 20th	Day	53% 6% 15% 20% 5%	1680
	21st to end	Day	54% 6% 18% 18% 4	1680
December	1st to 10th	Day	51% 11% 18% 12% 7%	2214
	11th to 20th	Day	61% 5% 21% 8% 5%	2320
	21st to end	Day	39% 5% 13% 23% 14% 6%	3500
January	1st to 10th	Night	52% 6% 14% 18% 9%	8769
	11th to 20th	Night	49% 5% 16% 17% 12% 1	8820
	21st to end	Night	46% 8% 19% 20% 7%	9222
February	1st to 10th	Night	52% 6% 15% 17% 10% 1	2812
	11th to 20th	Night	48% 6% 13% 19% 13% 1	2663
	21st to end	Night	44% 5% 16% 23% 11%	2222
March	1st to 10th	Night	45% 6% 20% 23% 6%	5460
	11th to 20th	Night	48% 6% 16% 22% 7%	5110
	21st to end	Night	55% 6% 10% 20% 8%	5376
April	1st to 10th	Night	39% 8% 16% 23% 14% 1	2100
	11th to 20th	Night	50% 6% 11% 20% 11% 2	1975
	21st to end	Night	47% 6% 11% 24% 11% 1	1743
May	1st to 10th	Night	38% 5% 9% 26% 18% 3	4724
	11th to 20th	Night	51% 6% 10% 20% 12% 1	4702
	21st to end	Night	35% 6% 13% 30% 14% 1	4773
June	1st to 10th	Night	37% 5% 15% 27% 14% 1	1418
	11th to 20th	Night	44% 8% 13% 21% 12% 1	1260
	21st to end	Night	31% 7% 19% 31% 12% 1	1376
July	1st to 10th	Night	28% 7% 24% 31% 10%	3145
	11th to 20th	Night	28% 7% 14% 38% 12% 1	3138
	21st to end	Night	21% 5% 18% 36% 17% 2	3607
August	1st to 10th	Night	27% 5% 19% 32% 15% 2	2600
	11th to 20th	Night	24% 7% 16% 35% 16% 1	2783
	21st to end	Night	26% 6% 11% 36% 19% 2	3358
September	1st to 10th	Night	29% 6% 13% 29% 17% 7%	2000
	11th to 20th	Night	34% 7% 14% 29% 13% 3	2000
	21st to end	Night	28% 5% 11% 34% 19% 3	2278
October	1st to 10th	Night	35% 4 17% 30% 14%	3920
	11th to 20th	Night	28% 4 15% 38% 15% 1	3898
	21st to end	Night	38% 5% 11% 35% 9% 1	4652
November	1st to 10th	Night	52% 7% 13% 19% 8% 1	2870
	11th to 20th	Night	48% 8% 18% 18% 7% 1	2940
	21st to end	Night	50% 7% 17% 22% 4	2940
December	1st to 10th	Night	60% 6% 18% 12% 4	5169
	11th to 20th	Night	58% 7% 19% 12% 3	6091
	21st to end	Night	38% 5% 12% 27% 14% 4	7691

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% 25% 29% 19% 4	220
	11th to 20th	Day	9% 12% 35% 28% 16%	220
	21st to end	Day	8% 16% 31% 31% 14% 1	323
February	1st to 10th	Day	11% 15% 37% 27% 8% 3	330
	11th to 20th	Day	8% 8% 31% 33% 14% 5%	330
	21st to end	Day	5% 10% 38% 32% 11% 5%	273
March	1st to 10th	Day	9% 12% 33% 27% 15% 4	336
	11th to 20th	Day	10% 12% 36% 28% 11% 4	540
	21st to end	Day	13% 10% 34% 25% 15% 3	594
April	1st to 10th	Day	9% 16% 34% 29% 10% 2	540
	11th to 20th	Day	14% 16% 35% 26% 8% 2	532
	21st to end	Day	17% 10% 30% 29% 13% 1	687
May	1st to 10th	Day	14% 8% 25% 30% 19% 4	753
	11th to 20th	Day	12% 11% 25% 31% 16% 5%	775
	21st to end	Day	14% 9% 22% 27% 22% 6%	844
June	1st to 10th	Day	15% 11% 30% 27% 14% 4	780
	11th to 20th	Day	18% 13% 30% 25% 12% 3	780
	21st to end	Day	12% 9% 23% 33% 19% 5%	780
July	1st to 10th	Day	7% 5% 24% 35% 22% 6%	722
	11th to 20th	Day	11% 6% 25% 32% 20% 6%	718
	21st to end	Day	7% 7% 22% 27% 28% 9%	794
August	1st to 10th	Day	10% 4 21% 34% 23% 7%	726
	11th to 20th	Day	9% 6% 22% 34% 20% 8%	606
	21st to end	Day	10% 7% 24% 32% 20% 7%	583
September	1st to 10th	Day	10% 9% 26% 31% 18% 5%	530
	11th to 20th	Day	15% 8% 27% 31% 16% 3	530
	21st to end	Day	14% 8% 33% 27% 14% 4	402
October	1st to 10th	Day	17% 6% 28% 27% 17% 5%	330
	11th to 20th	Day	8% 13% 35% 26% 14% 4	330
	21st to end	Day	9% 12% 42% 24% 9% 2	363
November	1st to 10th	Day	19% 12% 35% 23% 9% 2	330
	11th to 20th	Day	14% 14% 35% 27% 9% 1	330
	21st to end	Day	6% 11% 40% 26% 13% 3	330
December	1st to 10th	Day	9% 8% 43% 28% 8% 3	272
	11th to 20th	Day	9% 12% 41% 28% 8% 2	220
	21st to end	Day	12% 5% 36% 26% 17% 3	242
January	1st to 10th	Night	8% 11% 36% 34% 11% 1	1050
	11th to 20th	Night	8% 15% 39% 30% 8% 1	1050
	21st to end	Night	10% 12% 39% 28% 10% 1	1155
February	1st to 10th	Night	11% 8% 31% 37% 12% 1	922
	11th to 20th	Night	9% 8% 33% 37% 11% 1	824
	21st to end	Night	6% 7% 27% 37% 19% 4	692
March	1st to 10th	Night	10% 7% 33% 35% 13% 1	840
	11th to 20th	Night	9% 8% 33% 36% 12% 2	840
	21st to end	Night	12% 7% 31% 34% 14% 2	819
April	1st to 10th	Night	11% 8% 28% 40% 10% 1	630
	11th to 20th	Night	15% 10% 35% 33% 7% 1	623
	21st to end	Night	16% 8% 32% 31% 13%	630
May	1st to 10th	Night	13% 7% 26% 36% 18% 1	630
	11th to 20th	Night	14% 7% 28% 32% 17% 2	621
	21st to end	Night	18% 5% 22% 34% 18% 4	547
June	1st to 10th	Night	13% 8% 29% 33% 15% 2	420
	11th to 20th	Night	14% 10% 25% 35% 16%	420
	21st to end	Night	8% 7% 25% 39% 20% 2	420
July	1st to 10th	Night	8% 5% 17% 47% 23% 1	390
	11th to 20th	Night	6% 4 26% 43% 18% 2	388
	21st to end	Night	4 4 24% 44% 22% 2	543
August	1st to 10th	Night	6% 5% 23% 41% 22% 3	597
	11th to 20th	Night	5% 5% 20% 41% 28% 2	594
	21st to end	Night	8% 5% 24% 39% 22% 2	660
September	1st to 10th	Night	10% 4 27% 39% 19% 2	600
	11th to 20th	Night	12% 6% 19% 45% 17% 1	600
	21st to end	Night	11% 6% 31% 37% 14% 1	750
October	1st to 10th	Night	16% 7% 29% 34% 15%	800
	11th to 20th	Night	9% 9% 33% 33% 14% 1	800
	21st to end	Night	12% 13% 36% 30% 8%	1076
November	1st to 10th	Night	19% 10% 33% 30% 8% 1	1025
	11th to 20th	Night	9% 13% 35% 31% 10% 2	1050
	21st to end	Night	11% 11% 38% 31% 7% 1	1050
December	1st to 10th	Night	10% 10% 36% 30% 13% 1	1050
	11th to 20th	Night	11% 11% 38% 29% 10% 1	1050
	21st to end	Night	9% 9% 33% 33% 13% 3	1155

Page generated at 2026-06-28 00:10:49. Version ac07

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