Hords Creek Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hords Creek Lake clear sky chart from 2005-11-06 to 2026-02-01.

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% 4 2 4 3 3 4 3 5% 6% 57%	127490
	Night	7% 4 2 4 3 3 3 3 5% 7% 60%	124842
Transparency	Day	27% 4 9% 22% 25% 13%	131321
	Night	25% 4 8% 22% 26% 16%	129074
Seeing	Day	9% 7% 23% 30% 23% 8%	16615
	Night	9% 6% 29% 39% 15% 1	26651

By Month

Percentage Cloud Cover SE (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	9% 5% 3 5% 3 3 3 2 4 6% 57%	4167
	11th to 20th	Day	5% 6% 1 3 2 2 2 3 4 5% 66%	4170
	21st to end	Day	16% 6% 2 4 3 2 3 3 4 4 52%	5037
February	1st to 10th	Day	11% 5% 2 4 4 3 3 3 5% 6% 55%	2000
	11th to 20th	Day	11% 8% 2 6% 3 3 3 2 3 6% 54%	1949
	21st to end	Day	12% 7% 1 4 3 2 3 2 4 5% 57%	1650
March	1st to 10th	Day	9% 5% 2 5% 4 3 3 3 4 6% 57%	4627
	11th to 20th	Day	10% 5% 2 4 3 3 3 3 5% 5% 58%	4980
	21st to end	Day	5% 4 2 5% 4 4 4 4 5% 7% 55%	5462
April	1st to 10th	Day	7% 5% 2 5% 4 4 3 3 5% 6% 55%	2225
	11th to 20th	Day	11% 6% 2 5% 3 3 3 3 5% 6% 54%	2374
	21st to end	Day	7% 5% 2 5% 3 3 3 3 4 6% 58%	2485
May	1st to 10th	Day	11% 6% 2 5% 3 4 3 3 5% 5% 52%	5862
	11th to 20th	Day	11% 6% 2 6% 3 3 4 3 5% 6% 51%	5862
	21st to end	Day	9% 6% 2 6% 4 4 4 3 6% 8% 48%	6434
June	1st to 10th	Day	5% 2 1 4 4 3 4 4 6% 7% 60%	2600
	11th to 20th	Day	4 3 1 4 4 4 4 3 6% 8% 60%	2600
	21st to end	Day	6% 3 1 4 4 4 4 4 6% 8% 57%	2600
July	1st to 10th	Day	12% 5% 2 6% 5% 5% 5% 3 6% 7% 44%	5900
	11th to 20th	Day	3 3 1 4 3 3 4 3 6% 9% 61%	5900
	21st to end	Day	3 2 1 3 3 3 4 4 6% 9% 63%	6422
August	1st to 10th	Day	1 1 1 3 3 3 3 3 4 7% 73%	4073
	11th to 20th	Day	3 2 1 3 2 3 3 4 5% 8% 65%	3846
	21st to end	Day	3 2 1 5% 4 4 4 4 5% 9% 59%	4312
September	1st to 10th	Day	9% 5% 2 4 5% 4 5% 3 5% 6% 52%	2215
	11th to 20th	Day	9% 5% 2 6% 4 4 5% 4 5% 8% 51%	2200
	21st to end	Day	8% 2 2 4 3 3 4 2 5% 6% 60%	2200
October	1st to 10th	Day	5% 2 1 3 3 2 3 3 5% 7% 66%	2200
	11th to 20th	Day	8% 4 1 3 2 1 3 2 4 5% 67%	2142
	21st to end	Day	10% 4 2 4 2 2 2 2 3 4 65%	2200
November	1st to 10th	Day	9% 4 2 4 4 2 2 3 3 5% 62%	1918
	11th to 20th	Day	5% 3 2 4 2 3 3 2 5% 8% 64%	1890
	21st to end	Day	10% 5% 2 5% 3 2 3 3 4 5% 57%	1890
December	1st to 10th	Day	14% 6% 2 6% 4 4 4 3 3 4 51%	3030
	11th to 20th	Day	8% 6% 2 5% 3 3 4 4 4 4 57%	3481
	21st to end	Day	9% 5% 1 4 3 2 2 2 3 4 65%	4587
January	1st to 10th	Night	9% 6% 2 5% 3 3 3 2 4 5% 59%	6018
	11th to 20th	Night	5% 4 1 3 2 2 2 2 4 5% 71%	6030
	21st to end	Night	15% 7% 2 5% 3 3 3 3 4 5% 50%	6214
February	1st to 10th	Night	10% 5% 2 5% 4 3 2 2 4 5% 58%	2400
	11th to 20th	Night	11% 5% 3 5% 3 3 4 3 5% 5% 54%	2338
	21st to end	Night	11% 5% 1 3 3 3 2 2 5% 6% 59%	1980
March	1st to 10th	Night	6% 4 2 5% 3 4 4 3 5% 6% 58%	5239
	11th to 20th	Night	9% 5% 2 3 3 2 3 3 5% 6% 58%	4980
	21st to end	Night	6% 5% 2 4 3 3 4 3 5% 7% 58%	5467
April	1st to 10th	Night	6% 4 2 3 3 3 4 4 6% 8% 58%	2170
	11th to 20th	Night	9% 5% 2 5% 4 3 4 3 5% 6% 53%	1977
	21st to end	Night	7% 5% 1 4 3 2 4 2 5% 5% 62%	1914
May	1st to 10th	Night	13% 6% 2 5% 3 3 3 3 4 5% 53%	4053
	11th to 20th	Night	6% 5% 2 5% 4 4 5% 4 6% 7% 54%	4053
	21st to end	Night	9% 6% 2 5% 4 4 4 4 6% 10% 47%	4443
June	1st to 10th	Night	3 2 1 4 2 3 3 4 7% 11% 61%	1800
	11th to 20th	Night	4 2 1 3 2 3 4 4 6% 9% 64%	1800
	21st to end	Night	4 2 1 3 3 3 3 2 5% 8% 66%	1800
July	1st to 10th	Night	8% 5% 2 6% 3 4 4 3 6% 9% 49%	4078
	11th to 20th	Night	2 1 1 2 2 2 3 3 4 9% 71%	4077
	21st to end	Night	2 2 1 3 3 3 3 3 5% 8% 67%	4449
August	1st to 10th	Night	1 1 3 2 2 2 2 4 7% 75%	3081
	11th to 20th	Night	3 2 1 3 2 2 3 3 5% 9% 68%	3213
	21st to end	Night	2 2 1 3 3 3 5% 4 6% 8% 61%	3597
September	1st to 10th	Night	7% 3 1 5% 4 4 4 3 5% 8% 56%	2182
	11th to 20th	Night	8% 4 2 4 4 3 4 4 6% 8% 54%	2200
	21st to end	Night	7% 4 1 4 3 3 3 3 5% 7% 60%	2200
October	1st to 10th	Night	4 3 1 2 2 2 3 3 5% 8% 67%	2200
	11th to 20th	Night	8% 3 1 3 3 2 2 2 3 5% 66%	2235
	21st to end	Night	9% 4 2 4 2 2 2 2 3 4 65%	2640
November	1st to 10th	Night	10% 5% 1 3 2 2 3 2 4 5% 64%	2595
	11th to 20th	Night	4 3 1 4 2 3 3 3 4 6% 66%	2730
	21st to end	Night	11% 6% 2 5% 3 3 3 3 5% 5% 54%	2730
December	1st to 10th	Night	13% 6% 2 5% 3 3 3 2 4 5% 54%	4380
	11th to 20th	Night	7% 6% 2 6% 4 4 4 3 5% 6% 56%	4946
	21st to end	Night	9% 5% 2 4 3 3 3 2 3 4 63%	6633

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	29% 3 5% 22% 29% 12%	4168
	11th to 20th	Day	22% 2 4 22% 35% 15%	4170
	21st to end	Day	36% 3 4 14% 26% 18%	5037
February	1st to 10th	Day	31% 3 5% 17% 24% 21%	2000
	11th to 20th	Day	35% 2 6% 21% 21% 15%	1959
	21st to end	Day	32% 3 4 13% 27% 23%	1650
March	1st to 10th	Day	29% 3 4 11% 24% 28%	4627
	11th to 20th	Day	30% 3 8% 10% 19% 31%	4980
	21st to end	Day	27% 5% 7% 18% 27% 16%	5464
April	1st to 10th	Day	29% 4 9% 18% 21% 18%	2225
	11th to 20th	Day	33% 3 7% 17% 22% 17%	2374
	21st to end	Day	29% 4 7% 20% 28% 13%	2485
May	1st to 10th	Day	34% 5% 7% 16% 23% 15%	5900
	11th to 20th	Day	34% 4 7% 15% 28% 13%	5866
	21st to end	Day	33% 6% 10% 26% 16% 9%	6447
June	1st to 10th	Day	22% 6% 16% 28% 24% 5%	2600
	11th to 20th	Day	22% 5% 11% 30% 25% 7%	2600
	21st to end	Day	25% 5% 12% 27% 22% 9%	2600
July	1st to 10th	Day	39% 5% 13% 30% 12% 1	5836
	11th to 20th	Day	20% 5% 18% 34% 21% 3	5831
	21st to end	Day	18% 5% 15% 36% 24% 2	6240
August	1st to 10th	Day	13% 3 10% 34% 35% 4	4059
	11th to 20th	Day	18% 4 16% 35% 25% 4	3882
	21st to end	Day	22% 6% 17% 28% 22% 5%	4311
September	1st to 10th	Day	32% 5% 8% 22% 22% 11%	2215
	11th to 20th	Day	32% 6% 10% 21% 24% 7%	2200
	21st to end	Day	26% 3 8% 21% 27% 15%	2200
October	1st to 10th	Day	12% 3 7% 15% 33% 31%	3590
	11th to 20th	Day	19% 2 5% 25% 23% 25%	3473
	21st to end	Day	18% 2 4 23% 38% 15%	3538
November	1st to 10th	Day	27% 3 6% 22% 27% 15%	1918
	11th to 20th	Day	21% 3 8% 22% 27% 19%	1890
	21st to end	Day	31% 3 5% 20% 28% 14%	1890
December	1st to 10th	Day	39% 2 5% 17% 26% 11%	3030
	11th to 20th	Day	31% 3 7% 15% 27% 17%	3479
	21st to end	Day	26% 2 3 21% 31% 17%	4587
January	1st to 10th	Night	29% 3 5% 20% 31% 12%	6018
	11th to 20th	Night	18% 2 3 19% 35% 23%	6030
	21st to end	Night	38% 3 4 14% 23% 18%	6214
February	1st to 10th	Night	30% 2 6% 16% 24% 21%	2400
	11th to 20th	Night	32% 3 7% 18% 22% 19%	2338
	21st to end	Night	29% 4 5% 13% 24% 25%	1980
March	1st to 10th	Night	24% 5% 4 15% 28% 24%	5239
	11th to 20th	Night	27% 3 8% 15% 15% 32%	4980
	21st to end	Night	25% 5% 8% 19% 27% 16%	5467
April	1st to 10th	Night	24% 4 11% 21% 18% 22%	2170
	11th to 20th	Night	31% 4 9% 17% 22% 17%	1977
	21st to end	Night	24% 3 11% 24% 27% 11%	1914
May	1st to 10th	Night	34% 4 7% 21% 20% 13%	4080
	11th to 20th	Night	29% 6% 10% 18% 22% 17%	4054
	21st to end	Night	32% 6% 13% 23% 17% 9%	4452
June	1st to 10th	Night	18% 5% 18% 33% 23% 4	1800
	11th to 20th	Night	17% 4 12% 34% 25% 8%	1800
	21st to end	Night	19% 4 12% 31% 25% 9%	1800
July	1st to 10th	Night	32% 5% 14% 31% 16% 2	4035
	11th to 20th	Night	13% 3 13% 38% 29% 4	4026
	21st to end	Night	16% 4 16% 35% 27% 2	4320
August	1st to 10th	Night	11% 2 10% 30% 41% 5%	3071
	11th to 20th	Night	15% 4 17% 38% 23% 4	3243
	21st to end	Night	19% 7% 20% 28% 23% 4	3597
September	1st to 10th	Night	26% 6% 9% 25% 21% 12%	2182
	11th to 20th	Night	28% 5% 14% 23% 22% 8%	2200
	21st to end	Night	24% 4 7% 24% 23% 17%	2200
October	1st to 10th	Night	10% 3 7% 15% 29% 36%	3590
	11th to 20th	Night	18% 2 7% 18% 29% 25%	3630
	21st to end	Night	19% 2 3 23% 38% 15%	4252
November	1st to 10th	Night	26% 3 6% 20% 25% 20%	2595
	11th to 20th	Night	21% 3 6% 22% 28% 20%	2730
	21st to end	Night	33% 3 5% 17% 26% 16%	2730
December	1st to 10th	Night	33% 2 5% 21% 25% 14%	4380
	11th to 20th	Night	31% 3 6% 15% 28% 18%	4947
	21st to end	Night	27% 3 4 22% 26% 19%	6633

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% 17% 37% 28% 6% 1	330
	11th to 20th	Day	15% 15% 29% 28% 9% 2	330
	21st to end	Day	13% 14% 41% 25% 7% 1	363
February	1st to 10th	Day	17% 12% 38% 28% 5%	300
	11th to 20th	Day	19% 13% 43% 21% 4	300
	21st to end	Day	18% 14% 43% 18% 6% 1	249
March	1st to 10th	Day	16% 15% 39% 25% 5%	300
	11th to 20th	Day	15% 18% 35% 25% 7% 1	300
	21st to end	Day	13% 12% 43% 24% 8%	330
April	1st to 10th	Day	9% 18% 44% 21% 8%	325
	11th to 20th	Day	11% 17% 45% 22% 5%	492
	21st to end	Day	10% 13% 42% 27% 8%	585
May	1st to 10th	Day	11% 10% 36% 35% 7% 1	703
	11th to 20th	Day	14% 7% 30% 32% 13% 3	725
	21st to end	Day	10% 5% 30% 39% 15% 2	789
June	1st to 10th	Day	5% 2 18% 43% 27% 5%	730
	11th to 20th	Day	4 1 18% 47% 26% 4	730
	21st to end	Day	4 2 9% 38% 35% 11%	730
July	1st to 10th	Day	8% 2 4 31% 42% 14%	721
	11th to 20th	Day	4 1 3 29% 47% 16%	718
	21st to end	Day	2 1 4 28% 45% 21%	794
August	1st to 10th	Day	2 1 4 25% 47% 21%	630
	11th to 20th	Day	5% 1 4 29% 44% 17%	517
	21st to end	Day	5% 2 4 29% 39% 21%	583
September	1st to 10th	Day	10% 1 4 23% 35% 25%	345
	11th to 20th	Day	5% 1 5% 25% 45% 20%	330
	21st to end	Day	11% 2 5% 32% 37% 14%	330
October	1st to 10th	Day	4 2 11% 35% 35% 13%	330
	11th to 20th	Day	9% 4 25% 35% 23% 5%	330
	21st to end	Day	15% 9% 25% 25% 21% 4	363
November	1st to 10th	Day	14% 5% 28% 33% 15% 5%	330
	11th to 20th	Day	11% 11% 26% 33% 14% 5%	330
	21st to end	Day	14% 17% 31% 24% 12% 2	330
December	1st to 10th	Day	16% 10% 32% 30% 11% 2	330
	11th to 20th	Day	7% 12% 40% 29% 10% 2	330
	21st to end	Day	17% 10% 37% 24% 12% 1	363
January	1st to 10th	Night	12% 9% 36% 34% 9%	1050
	11th to 20th	Night	12% 10% 35% 35% 8%	1050
	21st to end	Night	14% 11% 36% 34% 6%	970
February	1st to 10th	Night	13% 10% 40% 30% 7%	800
	11th to 20th	Night	14% 11% 42% 28% 5%	784
	21st to end	Night	15% 12% 43% 26% 3	660
March	1st to 10th	Night	13% 10% 42% 31% 5%	743
	11th to 20th	Night	14% 11% 39% 30% 6%	600
	21st to end	Night	7% 12% 48% 30% 3	660
April	1st to 10th	Night	8% 10% 49% 27% 5%	600
	11th to 20th	Night	10% 11% 50% 27% 1	593
	21st to end	Night	8% 10% 51% 24% 8%	600
May	1st to 10th	Night	9% 7% 45% 35% 5%	600
	11th to 20th	Night	10% 4 38% 38% 9% 1	591
	21st to end	Night	9% 4 37% 38% 11% 1	650
June	1st to 10th	Night	3 3 25% 53% 16% 1	600
	11th to 20th	Night	4 2 24% 61% 11%	600
	21st to end	Night	5% 1 17% 53% 24% 1	600
July	1st to 10th	Night	8% 2 7% 48% 32% 3	585
	11th to 20th	Night	3 1 7% 52% 35% 2	582
	21st to end	Night	2 1 4 52% 39% 2	657
August	1st to 10th	Night	1 4 51% 42% 2	597
	11th to 20th	Night	5% 1 4 45% 40% 4	594
	21st to end	Night	3 1 2 43% 46% 5%	660
September	1st to 10th	Night	7% 1 10% 40% 37% 5%	600
	11th to 20th	Night	9% 2 9% 44% 36% 1	600
	21st to end	Night	9% 2 12% 46% 30% 2	600
October	1st to 10th	Night	6% 1 17% 48% 26% 2	600
	11th to 20th	Night	10% 4 26% 41% 18% 1	635
	21st to end	Night	12% 7% 27% 38% 15% 1	880
November	1st to 10th	Night	12% 3 27% 41% 16%	955
	11th to 20th	Night	5% 7% 31% 42% 13% 1	1050
	21st to end	Night	15% 8% 31% 34% 11% 1	1050
December	1st to 10th	Night	13% 7% 33% 38% 8%	1050
	11th to 20th	Night	12% 8% 35% 36% 8%	1050
	21st to end	Night	11% 8% 38% 35% 8%	1155

Page generated at 2026-01-29 00:21:41. Version ac07

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