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 2024-11-28.

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% 7% 57%	101205
	Night	7% 4 2 4 3 3 3 3 5% 7% 60%	98446
Transparency	Day	26% 4 9% 23% 25% 12%	105075
	Night	24% 4 9% 23% 26% 15%	102703
Seeing	Day	9% 7% 22% 30% 24% 8%	15079
	Night	9% 6% 29% 39% 16% 1	25021

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	8% 6% 2 5% 3 2 3 2 4 5% 60%	2847
	11th to 20th	Day	7% 6% 1 3 2 2 2 3 5% 6% 63%	2850
	21st to end	Day	12% 6% 2 5% 3 3 3 3 4 5% 54%	3435
February	1st to 10th	Day	10% 5% 2 4 4 3 3 3 5% 6% 54%	1900
	11th to 20th	Day	11% 8% 2 6% 3 3 3 2 4 6% 54%	1849
	21st to end	Day	12% 7% 1 4 3 2 3 2 4 4 57%	1570
March	1st to 10th	Day	11% 6% 2 6% 4 3 3 3 4 6% 52%	3218
	11th to 20th	Day	15% 7% 2 6% 3 3 3 3 5% 6% 46%	3480
	21st to end	Day	6% 5% 2 6% 5% 4 5% 4 6% 8% 51%	3814
April	1st to 10th	Day	6% 5% 3 5% 4 4 3 3 5% 7% 55%	2114
	11th to 20th	Day	11% 6% 2 5% 3 3 3 3 5% 6% 53%	2254
	21st to end	Day	7% 5% 2 5% 3 3 3 3 4 6% 58%	2361
May	1st to 10th	Day	10% 6% 3 6% 4 4 4 3 5% 6% 49%	4082
	11th to 20th	Day	13% 6% 2 5% 3 3 3 3 5% 6% 51%	4082
	21st to end	Day	9% 6% 2 6% 4 4 4 3 6% 8% 49%	4477
June	1st to 10th	Day	5% 2 1 4 4 4 4 4 6% 7% 60%	2470
	11th to 20th	Day	3 3 1 4 4 4 4 3 6% 8% 60%	2470
	21st to end	Day	6% 3 1 4 4 4 4 4 5% 8% 57%	2470
July	1st to 10th	Day	4 3 1 4 4 4 5% 4 6% 8% 57%	4120
	11th to 20th	Day	2 2 1 3 2 3 4 3 6% 9% 65%	4120
	21st to end	Day	4 3 1 4 3 4 4 4 6% 9% 59%	4465
August	1st to 10th	Day	1 1 1 2 3 3 3 3 4 7% 73%	3948
	11th to 20th	Day	4 2 1 3 2 3 3 3 5% 8% 66%	3726
	21st to end	Day	3 2 1 5% 4 4 4 4 5% 9% 59%	4180
September	1st to 10th	Day	10% 4 2 4 5% 4 5% 3 5% 6% 52%	2104
	11th to 20th	Day	9% 5% 2 6% 4 4 4 3 5% 8% 50%	2090
	21st to end	Day	8% 2 2 4 3 3 4 2 4 6% 60%	2090
October	1st to 10th	Day	5% 2 1 3 3 2 3 3 5% 7% 65%	2090
	11th to 20th	Day	8% 4 1 3 2 2 3 2 3 5% 66%	2035
	21st to end	Day	10% 5% 2 4 2 2 2 2 3 4 65%	2090
November	1st to 10th	Day	9% 4 2 4 4 2 2 3 3 5% 60%	1825
	11th to 20th	Day	5% 3 2 4 2 3 3 2 5% 8% 64%	1800
	21st to end	Day	11% 5% 2 5% 3 3 2 3 4 5% 57%	1773
December	1st to 10th	Day	11% 7% 2 4 3 3 3 3 4 5% 56%	1710
	11th to 20th	Day	8% 5% 2 5% 4 3 4 4 5% 5% 55%	2161
	21st to end	Day	10% 6% 1 4 3 2 2 2 3 4 62%	3135
January	1st to 10th	Night	9% 5% 2 4 2 2 3 2 4 5% 61%	4108
	11th to 20th	Night	7% 6% 1 3 2 2 2 2 3 4 67%	4120
	21st to end	Night	11% 7% 2 5% 3 3 3 3 4 5% 54%	4248
February	1st to 10th	Night	10% 5% 2 5% 4 3 2 2 4 6% 57%	2280
	11th to 20th	Night	11% 5% 3 5% 3 3 4 3 4 5% 55%	2218
	21st to end	Night	12% 5% 1 3 3 3 2 3 5% 6% 58%	1884
March	1st to 10th	Night	8% 5% 2 5% 3 4 4 3 5% 6% 57%	3641
	11th to 20th	Night	12% 6% 2 4 3 2 4 4 6% 7% 49%	3480
	21st to end	Night	5% 5% 2 5% 4 4 4 4 6% 7% 54%	3817
April	1st to 10th	Night	5% 4 2 3 3 3 4 4 6% 9% 57%	2062
	11th to 20th	Night	8% 5% 2 5% 4 3 4 3 5% 6% 53%	1877
	21st to end	Night	6% 5% 1 4 3 2 3 2 5% 5% 64%	1819
May	1st to 10th	Night	13% 7% 2 5% 3 2 3 3 4 5% 51%	2823
	11th to 20th	Night	8% 6% 2 5% 4 3 4 3 4 7% 55%	2823
	21st to end	Night	8% 4 2 5% 3 3 4 4 5% 9% 53%	3090
June	1st to 10th	Night	3 2 1 4 2 3 3 4 7% 10% 62%	1710
	11th to 20th	Night	3 2 1 3 2 3 4 4 6% 9% 64%	1710
	21st to end	Night	4 3 1 3 3 3 4 2 5% 7% 65%	1710
July	1st to 10th	Night	4 2 1 3 2 3 3 3 6% 9% 63%	2850
	11th to 20th	Night	2 1 2 2 2 2 3 4 10% 73%	2850
	21st to end	Night	2 3 2 3 3 3 3 3 5% 8% 63%	3098
August	1st to 10th	Night	1 1 3 2 2 2 2 4 7% 75%	2986
	11th to 20th	Night	3 2 1 3 2 2 3 2 5% 9% 68%	3113
	21st to end	Night	2 2 1 3 3 3 5% 5% 6% 8% 61%	3487
September	1st to 10th	Night	7% 3 1 5% 4 4 4 3 6% 8% 56%	2073
	11th to 20th	Night	8% 4 2 4 4 3 4 4 5% 7% 54%	2090
	21st to end	Night	7% 4 1 4 3 3 3 3 4 7% 60%	2090
October	1st to 10th	Night	5% 3 1 2 2 2 3 3 5% 8% 66%	2090
	11th to 20th	Night	9% 3 2 3 3 2 3 2 3 5% 65%	2123
	21st to end	Night	10% 4 2 4 2 2 3 2 3 4 64%	2508
November	1st to 10th	Night	10% 5% 1 3 2 2 3 2 4 5% 62%	2468
	11th to 20th	Night	4 3 1 4 2 3 3 3 4 6% 65%	2600
	21st to end	Night	11% 6% 2 5% 3 3 3 2 5% 5% 55%	2562
December	1st to 10th	Night	9% 5% 1 4 3 3 3 3 4 6% 59%	2470
	11th to 20th	Night	8% 5% 2 6% 4 4 4 3 4 6% 54%	3036
	21st to end	Night	10% 5% 2 4 3 3 3 3 4 4 60%	4532

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	28% 4 4 16% 32% 16%	2848
	11th to 20th	Day	24% 3 6% 19% 33% 16%	2850
	21st to end	Day	33% 3 5% 17% 31% 11%	3435
February	1st to 10th	Day	31% 3 5% 17% 24% 19%	1900
	11th to 20th	Day	34% 2 5% 21% 22% 16%	1859
	21st to end	Day	32% 3 4 13% 27% 22%	1570
March	1st to 10th	Day	34% 4 5% 10% 25% 22%	3218
	11th to 20th	Day	41% 4 11% 13% 21% 10%	3480
	21st to end	Day	29% 6% 9% 16% 25% 14%	3814
April	1st to 10th	Day	29% 4 9% 19% 20% 18%	2114
	11th to 20th	Day	33% 3 7% 17% 23% 17%	2254
	21st to end	Day	29% 3 6% 20% 29% 13%	2361
May	1st to 10th	Day	36% 5% 8% 16% 19% 15%	4120
	11th to 20th	Day	34% 4 8% 18% 27% 8%	4086
	21st to end	Day	33% 6% 12% 24% 14% 11%	4489
June	1st to 10th	Day	22% 6% 16% 28% 24% 5%	2470
	11th to 20th	Day	22% 5% 11% 30% 24% 8%	2470
	21st to end	Day	25% 5% 11% 26% 23% 9%	2470
July	1st to 10th	Day	24% 5% 15% 39% 15% 1	4056
	11th to 20th	Day	16% 4 15% 36% 25% 4	4051
	21st to end	Day	20% 5% 12% 36% 24% 2	4325
August	1st to 10th	Day	13% 3 11% 33% 36% 5%	3934
	11th to 20th	Day	18% 4 15% 35% 25% 4	3762
	21st to end	Day	22% 6% 17% 28% 22% 5%	4179
September	1st to 10th	Day	32% 5% 8% 22% 22% 11%	2104
	11th to 20th	Day	33% 6% 10% 20% 24% 7%	2090
	21st to end	Day	26% 4 8% 21% 26% 15%	2090
October	1st to 10th	Day	12% 3 6% 14% 33% 32%	3480
	11th to 20th	Day	20% 2 5% 25% 23% 26%	3366
	21st to end	Day	18% 2 4 24% 38% 14%	3428
November	1st to 10th	Day	28% 3 7% 23% 26% 14%	1825
	11th to 20th	Day	21% 3 8% 23% 26% 19%	1800
	21st to end	Day	31% 3 5% 20% 28% 15%	1773
December	1st to 10th	Day	32% 2 6% 19% 28% 12%	1710
	11th to 20th	Day	31% 3 9% 16% 25% 17%	2159
	21st to end	Day	28% 3 3 20% 30% 17%	3135
January	1st to 10th	Night	27% 3 3 17% 33% 17%	4108
	11th to 20th	Night	22% 2 4 20% 29% 22%	4120
	21st to end	Night	33% 3 5% 16% 27% 16%	4248
February	1st to 10th	Night	31% 2 7% 16% 23% 20%	2280
	11th to 20th	Night	32% 3 6% 17% 23% 20%	2218
	21st to end	Night	29% 4 5% 14% 24% 25%	1884
March	1st to 10th	Night	27% 5% 5% 14% 28% 21%	3641
	11th to 20th	Night	34% 4 12% 21% 17% 13%	3480
	21st to end	Night	27% 6% 11% 20% 26% 10%	3817
April	1st to 10th	Night	24% 4 10% 22% 18% 21%	2062
	11th to 20th	Night	31% 4 9% 18% 21% 17%	1877
	21st to end	Night	23% 2 11% 25% 28% 10%	1819
May	1st to 10th	Night	35% 5% 8% 20% 19% 13%	2850
	11th to 20th	Night	29% 6% 11% 22% 22% 10%	2824
	21st to end	Night	28% 5% 13% 25% 19% 9%	3099
June	1st to 10th	Night	17% 5% 18% 33% 23% 4	1710
	11th to 20th	Night	16% 5% 13% 33% 25% 8%	1710
	21st to end	Night	20% 4 11% 30% 26% 10%	1710
July	1st to 10th	Night	18% 5% 15% 40% 20% 3	2805
	11th to 20th	Night	10% 3 12% 40% 30% 5%	2796
	21st to end	Night	19% 4 12% 37% 27% 1	2999
August	1st to 10th	Night	11% 2 10% 30% 41% 6%	2976
	11th to 20th	Night	15% 4 17% 37% 24% 4	3143
	21st to end	Night	19% 7% 20% 28% 23% 4	3487
September	1st to 10th	Night	26% 6% 10% 25% 21% 13%	2073
	11th to 20th	Night	29% 5% 14% 22% 22% 9%	2090
	21st to end	Night	24% 4 8% 24% 23% 18%	2090
October	1st to 10th	Night	10% 3 7% 15% 29% 36%	3480
	11th to 20th	Night	19% 2 7% 17% 29% 26%	3518
	21st to end	Night	19% 2 3 23% 39% 14%	4120
November	1st to 10th	Night	27% 3 6% 20% 24% 19%	2468
	11th to 20th	Night	21% 3 6% 22% 27% 21%	2600
	21st to end	Night	32% 3 5% 17% 27% 16%	2562
December	1st to 10th	Night	28% 2 7% 20% 26% 16%	2470
	11th to 20th	Night	32% 3 5% 16% 25% 18%	3037
	21st to end	Night	29% 3 3 17% 27% 20%	4532

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% 16% 37% 29% 6% 1	270
	11th to 20th	Day	16% 14% 27% 29% 11% 3	270
	21st to end	Day	10% 15% 40% 26% 8% 1	297
February	1st to 10th	Day	17% 13% 38% 27% 5%	270
	11th to 20th	Day	19% 11% 44% 21% 4	270
	21st to end	Day	20% 14% 44% 17% 4 1	225
March	1st to 10th	Day	16% 13% 39% 26% 5%	270
	11th to 20th	Day	15% 16% 34% 26% 8% 1	270
	21st to end	Day	14% 13% 42% 23% 7%	297
April	1st to 10th	Day	8% 17% 45% 22% 7%	294
	11th to 20th	Day	12% 17% 44% 22% 5%	452
	21st to end	Day	10% 13% 41% 27% 8%	541
May	1st to 10th	Day	11% 10% 36% 35% 7% 1	653
	11th to 20th	Day	15% 7% 28% 33% 14% 4	675
	21st to end	Day	10% 5% 29% 39% 15% 2	734
June	1st to 10th	Day	4 2 17% 43% 29% 6%	680
	11th to 20th	Day	4 1 18% 46% 27% 4	680
	21st to end	Day	4 2 9% 38% 35% 11%	680
July	1st to 10th	Day	6% 1 4 31% 44% 14%	671
	11th to 20th	Day	3 3 29% 48% 17%	668
	21st to end	Day	1 1 4 27% 46% 21%	739
August	1st to 10th	Day	2 1 3 25% 46% 22%	585
	11th to 20th	Day	5% 1 4 29% 45% 17%	477
	21st to end	Day	5% 2 4 28% 40% 20%	539
September	1st to 10th	Day	10% 1 4 21% 37% 27%	314
	11th to 20th	Day	5% 1 4 24% 44% 22%	300
	21st to end	Day	11% 1 5% 32% 36% 15%	300
October	1st to 10th	Day	4 2 12% 36% 34% 12%	300
	11th to 20th	Day	10% 3 26% 34% 23% 4	300
	21st to end	Day	16% 9% 25% 24% 22% 5%	330
November	1st to 10th	Day	15% 5% 29% 34% 13% 4	300
	11th to 20th	Day	11% 12% 28% 31% 13% 5%	300
	21st to end	Day	14% 18% 30% 23% 13% 2	291
December	1st to 10th	Day	17% 8% 30% 32% 11% 2	270
	11th to 20th	Day	7% 12% 42% 30% 9% 1	270
	21st to end	Day	19% 10% 37% 25% 9%	297
January	1st to 10th	Night	12% 9% 35% 35% 9%	950
	11th to 20th	Night	13% 9% 34% 35% 8%	950
	21st to end	Night	13% 10% 35% 36% 6%	878
February	1st to 10th	Night	13% 11% 39% 30% 6%	760
	11th to 20th	Night	14% 10% 42% 29% 5%	744
	21st to end	Night	15% 12% 45% 25% 3	628
March	1st to 10th	Night	13% 8% 42% 31% 5%	706
	11th to 20th	Night	15% 10% 39% 31% 6%	570
	21st to end	Night	7% 12% 47% 30% 3	627
April	1st to 10th	Night	7% 10% 51% 27% 5%	570
	11th to 20th	Night	10% 11% 50% 28% 1	563
	21st to end	Night	8% 10% 52% 23% 8%	570
May	1st to 10th	Night	8% 7% 45% 35% 4	570
	11th to 20th	Night	10% 4 37% 38% 10% 1	561
	21st to end	Night	9% 4 37% 38% 12% 1	617
June	1st to 10th	Night	3 3 24% 54% 16% 1	570
	11th to 20th	Night	3 2 24% 60% 11%	570
	21st to end	Night	5% 1 17% 51% 25% 1	570
July	1st to 10th	Night	6% 2 7% 49% 33% 3	555
	11th to 20th	Night	3 1 7% 53% 35% 3	552
	21st to end	Night	2 1 4 52% 39% 2	624
August	1st to 10th	Night	1 4 52% 42% 2	567
	11th to 20th	Night	6% 1 4 44% 40% 4	564
	21st to end	Night	3 1 2 43% 46% 5%	627
September	1st to 10th	Night	7% 1 10% 39% 38% 5%	570
	11th to 20th	Night	9% 2 9% 43% 36% 1	570
	21st to end	Night	9% 2 11% 46% 31% 2	570
October	1st to 10th	Night	6% 1 18% 47% 26% 2	570
	11th to 20th	Night	10% 4 27% 40% 18% 1	603
	21st to end	Night	13% 6% 27% 38% 15% 2	836
November	1st to 10th	Night	13% 3 27% 41% 16%	908
	11th to 20th	Night	6% 7% 32% 41% 13% 1	1000
	21st to end	Night	15% 8% 31% 34% 11% 1	986
December	1st to 10th	Night	13% 7% 32% 39% 9%	950
	11th to 20th	Night	12% 9% 35% 37% 7%	950
	21st to end	Night	11% 8% 39% 35% 8%	1045

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