Davis Creek Reservoir
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Davis Creek Reservoir clear sky chart from 2005-11-06 to 2024-11-10.

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	9% 6% 2 6% 4 4 4 3 5% 7% 50%	105219
	Night	9% 6% 2 5% 4 3 4 3 5% 7% 51%	102556
Transparency	Day	33% 6% 14% 26% 17% 3	104974
	Night	32% 6% 13% 27% 19% 4	102391
Seeing	Day	12% 9% 31% 31% 14% 2	15819
	Night	11% 9% 35% 35% 9%	25709

By Month

Percentage Cloud Cover SW (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% 13% 4 9% 5% 4 5% 3 4 7% 39%	2538
	11th to 20th	Day	6% 11% 3 10% 4 6% 7% 4 5% 7% 38%	2553
	21st to end	Day	5% 9% 4 11% 5% 4 4 2 4 5% 46%	3135
February	1st to 10th	Day	9% 9% 4 10% 5% 4 4 4 5% 8% 38%	1710
	11th to 20th	Day	7% 9% 3 7% 4 4 4 3 6% 7% 47%	1844
	21st to end	Day	9% 8% 2 6% 3 4 4 2 5% 6% 50%	1570
March	1st to 10th	Day	10% 6% 2 5% 3 4 3 4 4 5% 54%	3187
	11th to 20th	Day	10% 8% 3 5% 3 3 3 3 4 5% 54%	3480
	21st to end	Day	15% 11% 4 6% 4 4 4 4 5% 7% 35%	3814
April	1st to 10th	Day	11% 7% 3 6% 4 4 3 3 5% 7% 47%	2202
	11th to 20th	Day	14% 8% 2 6% 4 4 3 3 5% 7% 43%	2372
	21st to end	Day	17% 7% 2 5% 4 4 4 4 5% 8% 41%	2470
May	1st to 10th	Day	13% 6% 2 6% 5% 4 4 4 6% 6% 44%	4120
	11th to 20th	Day	14% 6% 2 5% 3 3 4 3 4 7% 49%	4082
	21st to end	Day	14% 6% 2 6% 5% 4 4 3 6% 7% 43%	4489
June	1st to 10th	Day	6% 4 2 5% 3 3 5% 4 7% 9% 52%	2596
	11th to 20th	Day	11% 4 2 5% 3 4 4 4 6% 7% 50%	2660
	21st to end	Day	4 4 2 4 3 3 4 4 7% 10% 55%	2660
July	1st to 10th	Day	11% 5% 2 5% 4 3 3 4 7% 9% 48%	4430
	11th to 20th	Day	6% 4 2 6% 4 4 5% 4 6% 9% 52%	4430
	21st to end	Day	4 4 2 5% 4 4 4 4 6% 9% 54%	4475
August	1st to 10th	Day	7% 6% 2 7% 4 5% 5% 4 7% 8% 45%	4103
	11th to 20th	Day	13% 7% 3 6% 4 4 4 4 6% 8% 42%	4041
	21st to end	Day	6% 5% 2 5% 3 3 3 3 5% 7% 59%	4388
September	1st to 10th	Day	12% 5% 2 4 3 3 3 3 4 6% 55%	2171
	11th to 20th	Day	8% 4 1 5% 4 4 4 3 4 6% 58%	2090
	21st to end	Day	11% 4 2 3 2 2 3 2 4 5% 62%	2090
October	1st to 10th	Day	8% 3 1 3 2 1 2 2 3 4 71%	3428
	11th to 20th	Day	6% 3 1 4 2 3 3 2 4 7% 64%	3140
	21st to end	Day	9% 5% 2 5% 3 3 3 3 4 6% 56%	3183
November	1st to 10th	Day	8% 5% 2 4 4 4 5% 4 6% 7% 52%	1754
	11th to 20th	Day	6% 6% 2 5% 4 4 3 3 5% 5% 57%	1710
	21st to end	Day	9% 8% 3 5% 3 4 3 3 5% 6% 51%	1710
December	1st to 10th	Day	7% 7% 3 7% 3 3 3 3 6% 8% 50%	1710
	11th to 20th	Day	6% 7% 3 7% 4 4 5% 3 6% 7% 47%	2090
	21st to end	Day	11% 14% 4 12% 4 4 4 3 4 5% 36%	2794
January	1st to 10th	Night	8% 12% 3 9% 6% 4 4 4 6% 7% 37%	4417
	11th to 20th	Night	5% 9% 3 7% 4 4 5% 4 7% 6% 46%	4401
	21st to end	Night	5% 9% 5% 12% 5% 4 4 3 5% 7% 41%	4532
February	1st to 10th	Night	9% 10% 4 8% 4 3 4 4 5% 6% 43%	2470
	11th to 20th	Night	5% 9% 3 7% 5% 5% 5% 4 6% 7% 45%	2237
	21st to end	Night	6% 8% 2 6% 4 4 4 3 4 6% 53%	1884
March	1st to 10th	Night	10% 6% 2 5% 3 3 3 3 4 5% 55%	3675
	11th to 20th	Night	9% 6% 2 5% 3 2 4 3 4 6% 56%	3480
	21st to end	Night	16% 9% 3 5% 4 4 4 4 5% 8% 38%	3817
April	1st to 10th	Night	12% 7% 2 5% 4 3 4 4 5% 7% 46%	1975
	11th to 20th	Night	13% 6% 3 5% 4 4 4 3 6% 8% 44%	1756
	21st to end	Night	14% 6% 2 5% 3 3 4 3 5% 7% 47%	1710
May	1st to 10th	Night	18% 4 1 5% 4 3 4 3 5% 6% 45%	2850
	11th to 20th	Night	10% 6% 2 4 4 3 4 4 5% 10% 47%	2823
	21st to end	Night	15% 6% 2 5% 4 3 4 4 6% 8% 42%	3098
June	1st to 10th	Night	8% 4 1 4 3 3 4 4 7% 10% 52%	1578
	11th to 20th	Night	10% 4 2 4 3 4 3 2 6% 8% 54%	1520
	21st to end	Night	4 4 2 4 3 4 5% 4 6% 9% 56%	1520
July	1st to 10th	Night	8% 4 2 5% 4 3 3 3 5% 7% 56%	2540
	11th to 20th	Night	5% 3 2 4 4 4 5% 4 7% 10% 53%	2540
	21st to end	Night	3 3 1 4 3 3 3 4 6% 10% 60%	3087
August	1st to 10th	Night	6% 3 1 4 4 4 4 4 7% 10% 51%	2836
	11th to 20th	Night	10% 6% 2 5% 5% 4 4 4 5% 8% 48%	2798
	21st to end	Night	5% 3 1 4 3 4 5% 3 6% 9% 56%	3262
September	1st to 10th	Night	9% 3 1 4 2 2 3 2 4 5% 64%	2008
	11th to 20th	Night	7% 4 2 3 3 4 3 3 5% 6% 60%	2090
	21st to end	Night	8% 4 1 4 3 3 3 3 4 5% 62%	2090
October	1st to 10th	Night	9% 3 1 3 2 2 1 2 3 4 71%	3498
	11th to 20th	Night	7% 4 1 3 2 2 2 2 4 6% 66%	3779
	21st to end	Night	9% 4 2 4 3 3 3 3 4 7% 57%	4371
November	1st to 10th	Night	6% 4 1 4 2 4 4 4 6% 7% 58%	2529
	11th to 20th	Night	8% 6% 2 4 4 3 3 3 5% 6% 57%	2470
	21st to end	Night	7% 7% 3 5% 3 3 3 3 5% 7% 55%	2470
December	1st to 10th	Night	6% 8% 2 6% 5% 4 4 3 4 6% 53%	2470
	11th to 20th	Night	7% 6% 3 5% 4 3 3 4 6% 8% 51%	3102
	21st to end	Night	14% 11% 3 9% 3 3 3 4 5% 6% 39%	4873

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	43% 8% 13% 25% 10% 1	2539
	11th to 20th	Day	44% 6% 19% 15% 13% 2	2553
	21st to end	Day	40% 6% 17% 21% 15% 1	3135
February	1st to 10th	Day	44% 7% 14% 21% 12% 2	1710
	11th to 20th	Day	36% 6% 15% 23% 16% 4	1854
	21st to end	Day	35% 5% 15% 24% 15% 6%	1570
March	1st to 10th	Day	31% 5% 10% 25% 26% 3	3187
	11th to 20th	Day	33% 5% 11% 30% 19% 2	3480
	21st to end	Day	45% 8% 22% 19% 5%	3814
April	1st to 10th	Day	36% 6% 14% 27% 14% 2	2202
	11th to 20th	Day	39% 6% 15% 22% 15% 3	2375
	21st to end	Day	41% 6% 12% 27% 13% 1	2470
May	1st to 10th	Day	37% 7% 14% 22% 16% 5%	4120
	11th to 20th	Day	34% 7% 14% 29% 15% 1	4086
	21st to end	Day	39% 7% 12% 30% 11% 1	4489
June	1st to 10th	Day	26% 8% 20% 31% 13% 2	2596
	11th to 20th	Day	31% 7% 15% 25% 18% 4	2660
	21st to end	Day	22% 9% 18% 31% 17% 4	2660
July	1st to 10th	Day	31% 6% 13% 31% 17% 2	4361
	11th to 20th	Day	28% 7% 14% 32% 16% 3	4355
	21st to end	Day	23% 9% 16% 27% 21% 5%	4333
August	1st to 10th	Day	33% 9% 14% 24% 15% 4	4090
	11th to 20th	Day	39% 7% 14% 24% 15% 1	4080
	21st to end	Day	26% 6% 15% 24% 21% 8%	4387
September	1st to 10th	Day	30% 5% 13% 23% 22% 6%	2171
	11th to 20th	Day	26% 7% 13% 31% 21% 3	2090
	21st to end	Day	26% 4 9% 32% 26% 3	2090
October	1st to 10th	Day	19% 3 6% 23% 39% 10%	3428
	11th to 20th	Day	22% 4 12% 36% 20% 7%	3140
	21st to end	Day	30% 4 11% 30% 22% 4	3183
November	1st to 10th	Day	30% 6% 15% 26% 20% 3	1754
	11th to 20th	Day	28% 6% 12% 27% 23% 5%	1710
	21st to end	Day	34% 4 13% 28% 18% 4	1710
December	1st to 10th	Day	33% 6% 14% 30% 14% 3	1710
	11th to 20th	Day	35% 6% 15% 32% 12%	2088
	21st to end	Day	51% 5% 8% 24% 11% 1	2794
January	1st to 10th	Night	44% 6% 10% 26% 13% 1	4417
	11th to 20th	Night	36% 6% 16% 29% 13% 1	4401
	21st to end	Night	42% 7% 14% 23% 14% 1	4532
February	1st to 10th	Night	42% 6% 13% 23% 14% 3	2470
	11th to 20th	Night	35% 8% 14% 26% 14% 4	2237
	21st to end	Night	32% 5% 12% 25% 21% 6%	1884
March	1st to 10th	Night	30% 5% 10% 25% 24% 5%	3675
	11th to 20th	Night	28% 5% 9% 27% 27% 3	3480
	21st to end	Night	43% 9% 19% 21% 7% 1	3817
April	1st to 10th	Night	36% 7% 15% 24% 17% 2	1975
	11th to 20th	Night	37% 7% 14% 26% 15% 2	1756
	21st to end	Night	35% 8% 13% 26% 17% 1	1710
May	1st to 10th	Night	38% 7% 11% 26% 14% 4	2850
	11th to 20th	Night	31% 9% 17% 25% 18%	2824
	21st to end	Night	37% 9% 16% 24% 12% 3	3099
June	1st to 10th	Night	26% 8% 20% 30% 14% 2	1578
	11th to 20th	Night	30% 7% 13% 28% 17% 5%	1520
	21st to end	Night	23% 7% 18% 30% 19% 3	1520
July	1st to 10th	Night	28% 5% 15% 36% 14% 2	2500
	11th to 20th	Night	25% 8% 15% 33% 16% 3	2492
	21st to end	Night	18% 8% 17% 28% 22% 6%	2990
August	1st to 10th	Night	27% 7% 18% 28% 15% 4	2826
	11th to 20th	Night	35% 6% 18% 27% 12% 2	2825
	21st to end	Night	24% 6% 14% 28% 19% 8%	3262
September	1st to 10th	Night	23% 4 10% 27% 27% 9%	2008
	11th to 20th	Night	24% 6% 12% 31% 22% 4	2090
	21st to end	Night	25% 5% 9% 28% 29% 5%	2090
October	1st to 10th	Night	19% 3 6% 16% 47% 8%	3498
	11th to 20th	Night	21% 3 12% 29% 24% 11%	3779
	21st to end	Night	28% 4 11% 28% 26% 3	4371
November	1st to 10th	Night	23% 6% 14% 27% 24% 6%	2529
	11th to 20th	Night	29% 4 11% 28% 23% 5%	2470
	21st to end	Night	30% 4 12% 28% 22% 3	2470
December	1st to 10th	Night	32% 5% 14% 28% 17% 3	2470
	11th to 20th	Night	30% 5% 14% 35% 16% 1	3103
	21st to end	Night	46% 5% 12% 26% 10% 1	4873

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	15% 12% 34% 27% 9% 3	270
	11th to 20th	Day	17% 14% 33% 27% 9%	270
	21st to end	Day	11% 10% 43% 26% 9% 1	297
February	1st to 10th	Day	13% 12% 44% 24% 6%	270
	11th to 20th	Day	11% 11% 45% 22% 8% 2	270
	21st to end	Day	17% 17% 42% 20% 4	225
March	1st to 10th	Day	11% 14% 38% 31% 5% 1	270
	11th to 20th	Day	19% 9% 37% 28% 7%	270
	21st to end	Day	23% 14% 35% 22% 5% 1	297
April	1st to 10th	Day	17% 22% 38% 19% 3 1	382
	11th to 20th	Day	19% 17% 35% 24% 5%	573
	21st to end	Day	20% 14% 32% 22% 9% 2	650
May	1st to 10th	Day	15% 13% 35% 29% 7% 1	653
	11th to 20th	Day	18% 12% 32% 23% 14% 3	675
	21st to end	Day	15% 10% 32% 29% 13% 1	734
June	1st to 10th	Day	6% 6% 27% 35% 20% 6%	680
	11th to 20th	Day	10% 7% 33% 36% 13% 2	680
	21st to end	Day	5% 8% 30% 38% 15% 2	680
July	1st to 10th	Day	7% 3 22% 39% 25% 4	671
	11th to 20th	Day	3 3 22% 45% 24% 3	668
	21st to end	Day	6% 4 19% 44% 24% 3	739
August	1st to 10th	Day	9% 2 21% 42% 23% 2	676
	11th to 20th	Day	8% 4 24% 41% 21% 2	665
	21st to end	Day	8% 3 25% 39% 21% 4	669
September	1st to 10th	Day	10% 5% 31% 34% 17% 3	381
	11th to 20th	Day	7% 6% 33% 34% 16% 4	300
	21st to end	Day	13% 11% 27% 31% 14% 4	300
October	1st to 10th	Day	19% 8% 22% 30% 15% 5%	300
	11th to 20th	Day	10% 14% 39% 26% 9% 2	300
	21st to end	Day	18% 14% 34% 26% 8% 1	330
November	1st to 10th	Day	13% 14% 39% 21% 10% 3	297
	11th to 20th	Day	10% 14% 45% 23% 7% 1	270
	21st to end	Day	18% 13% 36% 21% 10% 2	270
December	1st to 10th	Day	9% 9% 48% 26% 8% 1	270
	11th to 20th	Day	15% 13% 36% 26% 9% 1	270
	21st to end	Day	21% 13% 39% 24% 2 1	297
January	1st to 10th	Night	12% 11% 36% 34% 7%	950
	11th to 20th	Night	11% 13% 38% 30% 7% 1	950
	21st to end	Night	11% 10% 42% 30% 7%	1045
February	1st to 10th	Night	14% 11% 41% 29% 5%	950
	11th to 20th	Night	9% 11% 45% 29% 5% 1	763
	21st to end	Night	10% 11% 42% 31% 6%	628
March	1st to 10th	Night	11% 11% 45% 28% 5%	727
	11th to 20th	Night	14% 10% 40% 30% 6%	570
	21st to end	Night	20% 10% 41% 24% 5%	627
April	1st to 10th	Night	17% 13% 43% 25% 2	570
	11th to 20th	Night	17% 13% 41% 26% 3	563
	21st to end	Night	18% 10% 34% 30% 9%	570
May	1st to 10th	Night	14% 8% 38% 32% 7%	570
	11th to 20th	Night	14% 8% 38% 31% 9% 1	561
	21st to end	Night	16% 7% 32% 33% 10% 1	617
June	1st to 10th	Night	8% 5% 28% 46% 12% 2	570
	11th to 20th	Night	12% 5% 35% 37% 12%	570
	21st to end	Night	3 6% 30% 48% 13%	570
July	1st to 10th	Night	7% 3 21% 45% 23% 1	555
	11th to 20th	Night	4 2 21% 55% 18% 1	552
	21st to end	Night	5% 2 19% 56% 17%	624
August	1st to 10th	Night	7% 2 21% 50% 20% 1	567
	11th to 20th	Night	8% 2 24% 48% 18%	564
	21st to end	Night	8% 1 27% 45% 18% 1	627
September	1st to 10th	Night	9% 3 27% 46% 14% 2	570
	11th to 20th	Night	8% 4 32% 40% 15% 1	570
	21st to end	Night	9% 7% 34% 35% 14% 1	570
October	1st to 10th	Night	17% 6% 32% 31% 13%	575
	11th to 20th	Night	12% 13% 34% 31% 9%	760
	21st to end	Night	15% 11% 33% 31% 10%	986
November	1st to 10th	Night	9% 10% 36% 37% 7% 1	973
	11th to 20th	Night	11% 11% 39% 31% 8%	950
	21st to end	Night	10% 11% 36% 32% 10% 1	950
December	1st to 10th	Night	11% 11% 43% 30% 5%	950
	11th to 20th	Night	12% 10% 39% 31% 8%	950
	21st to end	Night	16% 12% 36% 29% 5%	1045

Page generated at 2024-11-07 05:55:46. Version ac07

Copyright © 2024 Attilla Danko.