Damer Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Damer Observing Site 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	14% 9% 3 8% 5% 4 4 4 6% 7% 36%	101339
	Night	15% 10% 4 8% 5% 4 4 3 5% 6% 36%	98244
Transparency	Day	45% 7% 12% 22% 13% 1	104951
	Night	46% 6% 11% 21% 14% 2	102773
Seeing	Day	17% 10% 27% 24% 16% 6%	15770
	Night	19% 9% 29% 29% 13% 1	25612

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	15% 15% 9% 12% 5% 4 5% 4 5% 6% 19%	2527
	11th to 20th	Day	14% 16% 8% 15% 6% 6% 5% 8% 6% 5% 12%	2530
	21st to end	Day	27% 20% 6% 11% 4 3 3 2 3 4 16%	2784
February	1st to 10th	Day	17% 15% 5% 11% 6% 5% 4 3 4 5% 24%	1871
	11th to 20th	Day	15% 12% 4 10% 6% 6% 4 3 4 5% 29%	1848
	21st to end	Day	16% 16% 5% 10% 5% 3 4 4 6% 5% 26%	1570
March	1st to 10th	Day	20% 17% 5% 9% 4 3 4 3 4 6% 26%	3120
	11th to 20th	Day	12% 8% 4 8% 5% 4 4 4 5% 7% 38%	3342
	21st to end	Day	18% 11% 5% 10% 6% 4 4 4 5% 7% 26%	4023
April	1st to 10th	Day	17% 12% 3 7% 5% 4 4 3 5% 7% 32%	2280
	11th to 20th	Day	17% 9% 2 7% 4 5% 4 4 5% 7% 35%	2254
	21st to end	Day	20% 8% 2 7% 5% 5% 4 3 6% 7% 33%	2457
May	1st to 10th	Day	18% 9% 2 7% 4 5% 5% 5% 6% 9% 30%	4082
	11th to 20th	Day	15% 7% 2 6% 4 4 4 4 6% 8% 38%	4081
	21st to end	Day	9% 6% 2 6% 4 4 5% 4 7% 9% 44%	4730
June	1st to 10th	Day	10% 5% 3 6% 5% 5% 5% 4 6% 8% 42%	2660
	11th to 20th	Day	9% 5% 2 5% 4 4 4 5% 6% 9% 45%	2660
	21st to end	Day	11% 6% 2 7% 5% 5% 5% 5% 6% 9% 39%	2660
July	1st to 10th	Day	13% 7% 3 7% 4 5% 4 5% 6% 9% 37%	4440
	11th to 20th	Day	7% 4 2 5% 4 4 5% 4 7% 11% 47%	4440
	21st to end	Day	8% 6% 2 7% 5% 5% 5% 5% 6% 8% 42%	4792
August	1st to 10th	Day	8% 4 2 6% 5% 4 5% 4 6% 8% 47%	4104
	11th to 20th	Day	9% 4 2 6% 4 4 5% 4 7% 9% 46%	3919
	21st to end	Day	6% 5% 2 5% 4 4 5% 4 6% 10% 50%	4180
September	1st to 10th	Day	9% 6% 2 6% 5% 4 5% 3 6% 8% 46%	2266
	11th to 20th	Day	11% 5% 1 4 4 4 5% 4 7% 8% 47%	2090
	21st to end	Day	13% 6% 2 5% 5% 5% 5% 4 6% 7% 43%	2090
October	1st to 10th	Day	13% 7% 2 6% 4 4 4 4 5% 6% 45%	2090
	11th to 20th	Day	17% 7% 2 6% 5% 4 4 4 6% 7% 38%	1898
	21st to end	Day	19% 10% 3 8% 5% 4 5% 3 6% 6% 30%	1881
November	1st to 10th	Day	11% 7% 2 6% 4 4 4 3 4 7% 47%	1762
	11th to 20th	Day	17% 13% 4 8% 5% 4 3 3 4 6% 33%	1800
	21st to end	Day	19% 12% 3 8% 5% 3 4 4 4 7% 30%	1773
December	1st to 10th	Day	16% 17% 5% 10% 7% 4 3 3 4 6% 26%	1634
	11th to 20th	Day	14% 16% 6% 12% 5% 5% 4 2 5% 5% 25%	1918
	21st to end	Day	24% 22% 8% 14% 5% 3 4 3 3 3 12%	2783
January	1st to 10th	Night	17% 16% 7% 12% 6% 4 4 3 5% 5% 22%	4428
	11th to 20th	Night	15% 20% 8% 15% 6% 3 5% 3 5% 4 17%	4440
	21st to end	Night	25% 17% 8% 11% 4 3 3 2 3 4 19%	4880
February	1st to 10th	Night	18% 15% 5% 9% 5% 5% 3 3 4 5% 28%	2308
	11th to 20th	Night	13% 12% 5% 8% 6% 6% 4 3 4 6% 33%	2218
	21st to end	Night	21% 13% 4 9% 4 4 3 4 5% 5% 30%	1884
March	1st to 10th	Night	17% 12% 4 8% 5% 4 3 3 4 6% 34%	3733
	11th to 20th	Night	11% 7% 2 7% 5% 4 4 4 5% 6% 44%	3617
	21st to end	Night	20% 9% 4 9% 4 4 4 4 5% 5% 34%	3638
April	1st to 10th	Night	15% 10% 3 6% 5% 4 4 4 6% 7% 37%	1900
	11th to 20th	Night	19% 8% 3 6% 4 4 4 4 5% 7% 37%	1875
	21st to end	Night	19% 8% 3 6% 4 4 4 5% 5% 6% 36%	1721
May	1st to 10th	Night	18% 8% 2 8% 5% 5% 4 4 6% 8% 32%	2813
	11th to 20th	Night	18% 8% 2 5% 4 4 4 3 6% 9% 37%	2812
	21st to end	Night	12% 6% 2 5% 5% 5% 5% 3 6% 7% 44%	2818
June	1st to 10th	Night	9% 5% 2 5% 4 3 4 4 6% 8% 50%	1520
	11th to 20th	Night	8% 5% 2 5% 5% 4 4 3 7% 8% 48%	1520
	21st to end	Night	10% 5% 3 6% 5% 4 5% 4 7% 9% 43%	1520
July	1st to 10th	Night	10% 4 2 6% 5% 5% 5% 4 6% 8% 45%	2530
	11th to 20th	Night	7% 4 2 5% 3 3 4 4 6% 8% 54%	2530
	21st to end	Night	7% 6% 2 6% 5% 5% 5% 4 7% 8% 43%	2768
August	1st to 10th	Night	10% 6% 2 5% 4 4 4 4 6% 9% 46%	2825
	11th to 20th	Night	7% 5% 2 5% 4 4 5% 3 6% 7% 51%	2907
	21st to end	Night	9% 5% 2 5% 4 3 4 3 5% 8% 52%	3476
September	1st to 10th	Night	10% 5% 2 5% 3 3 4 4 5% 7% 51%	1900
	11th to 20th	Night	9% 4 1 4 3 3 4 3 5% 7% 57%	2085
	21st to end	Night	13% 6% 2 5% 5% 3 4 2 5% 7% 48%	2090
October	1st to 10th	Night	10% 6% 2 5% 4 4 3 3 5% 6% 51%	2090
	11th to 20th	Night	17% 8% 2 6% 4 3 3 3 4 7% 44%	2279
	21st to end	Night	20% 8% 2 7% 3 4 4 3 5% 6% 37%	2717
November	1st to 10th	Night	13% 9% 3 5% 4 3 4 3 5% 7% 44%	2536
	11th to 20th	Night	15% 10% 3 8% 5% 4 4 4 6% 6% 34%	2600
	21st to end	Night	18% 14% 3 8% 5% 4 4 4 4 6% 30%	2562
December	1st to 10th	Night	16% 14% 4 9% 5% 4 4 3 4 6% 29%	2541
	11th to 20th	Night	16% 14% 7% 11% 6% 4 4 3 4 5% 25%	3279
	21st to end	Night	25% 19% 7% 10% 5% 5% 4 3 4 5% 14%	4884

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	64% 7% 11% 14% 5%	2528
	11th to 20th	Day	69% 6% 9% 11% 5%	2530
	21st to end	Day	75% 4 7% 11% 3	2784
February	1st to 10th	Day	62% 4 11% 14% 7% 1	1871
	11th to 20th	Day	56% 6% 9% 20% 8% 1	1858
	21st to end	Day	57% 6% 12% 17% 6% 1	1570
March	1st to 10th	Day	59% 6% 9% 18% 7%	3120
	11th to 20th	Day	43% 8% 11% 29% 9% 1	3342
	21st to end	Day	56% 10% 14% 17% 3	4023
April	1st to 10th	Day	51% 7% 11% 20% 11%	2280
	11th to 20th	Day	48% 6% 10% 22% 11% 3	2254
	21st to end	Day	49% 7% 12% 19% 10% 3	2457
May	1st to 10th	Day	48% 10% 13% 22% 7%	4120
	11th to 20th	Day	42% 9% 14% 25% 9% 1	4085
	21st to end	Day	33% 8% 13% 23% 21% 2	4743
June	1st to 10th	Day	37% 8% 11% 25% 15% 3	2660
	11th to 20th	Day	33% 8% 12% 24% 20% 3	2660
	21st to end	Day	40% 9% 15% 18% 15% 3	2660
July	1st to 10th	Day	43% 6% 13% 20% 15% 3	4371
	11th to 20th	Day	29% 8% 15% 29% 17% 1	4365
	21st to end	Day	40% 7% 15% 17% 18% 3	4641
August	1st to 10th	Day	32% 9% 15% 27% 15% 1	4091
	11th to 20th	Day	33% 7% 12% 29% 17% 1	3958
	21st to end	Day	29% 7% 15% 26% 20% 4	4179
September	1st to 10th	Day	35% 7% 13% 23% 18% 3	2266
	11th to 20th	Day	32% 7% 11% 25% 21% 3	2090
	21st to end	Day	38% 7% 11% 23% 19% 2	2090
October	1st to 10th	Day	27% 5% 9% 32% 25% 1	3480
	11th to 20th	Day	36% 5% 11% 22% 26% 1	3127
	21st to end	Day	44% 4 9% 28% 13% 2	3081
November	1st to 10th	Day	39% 5% 13% 26% 16% 2	1762
	11th to 20th	Day	53% 5% 11% 18% 11% 2	1800
	21st to end	Day	54% 6% 12% 20% 7% 1	1773
December	1st to 10th	Day	59% 6% 12% 15% 7%	1634
	11th to 20th	Day	62% 6% 8% 21% 3	1915
	21st to end	Day	78% 5% 6% 8% 3	2783
January	1st to 10th	Night	62% 8% 10% 14% 6%	4428
	11th to 20th	Night	72% 4 9% 11% 4	4440
	21st to end	Night	70% 4 9% 13% 5%	4880
February	1st to 10th	Night	59% 6% 11% 15% 8% 2	2308
	11th to 20th	Night	52% 6% 12% 20% 10% 1	2219
	21st to end	Night	56% 5% 12% 16% 10% 2	1884
March	1st to 10th	Night	50% 7% 11% 23% 8% 1	3733
	11th to 20th	Night	38% 7% 11% 27% 15% 2	3617
	21st to end	Night	50% 7% 14% 21% 6% 1	3638
April	1st to 10th	Night	44% 6% 13% 21% 14% 2	1900
	11th to 20th	Night	46% 6% 9% 20% 16% 3	1875
	21st to end	Night	46% 7% 10% 21% 14% 2	1721
May	1st to 10th	Night	47% 9% 11% 21% 11% 1	2840
	11th to 20th	Night	42% 9% 13% 25% 10% 1	2813
	21st to end	Night	37% 8% 10% 20% 21% 4	2826
June	1st to 10th	Night	31% 7% 13% 27% 19% 3	1520
	11th to 20th	Night	32% 8% 13% 23% 20% 4	1520
	21st to end	Night	37% 8% 15% 21% 16% 3	1520
July	1st to 10th	Night	36% 6% 14% 25% 13% 6%	2490
	11th to 20th	Night	26% 6% 15% 26% 25% 2	2482
	21st to end	Night	35% 8% 16% 17% 20% 4	2680
August	1st to 10th	Night	33% 7% 17% 28% 15% 1	2814
	11th to 20th	Night	30% 7% 13% 30% 19% 1	2934
	21st to end	Night	30% 6% 11% 28% 21% 3	3476
September	1st to 10th	Night	31% 6% 14% 24% 19% 6%	1900
	11th to 20th	Night	26% 6% 8% 28% 28% 3	2085
	21st to end	Night	36% 6% 10% 24% 21% 3	2090
October	1st to 10th	Night	22% 4 9% 33% 31% 1	3480
	11th to 20th	Night	34% 5% 8% 23% 29% 1	3789
	21st to end	Night	37% 4 9% 27% 21% 1	4467
November	1st to 10th	Night	40% 5% 11% 24% 18% 2	2536
	11th to 20th	Night	49% 5% 11% 20% 14% 2	2600
	21st to end	Night	55% 4 11% 21% 8%	2562
December	1st to 10th	Night	56% 6% 12% 17% 8% 1	2541
	11th to 20th	Night	60% 5% 12% 16% 6% 1	3281
	21st to end	Night	73% 6% 9% 9% 4	4884

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	23% 17% 37% 16% 6% 1	270
	11th to 20th	Day	24% 17% 36% 18% 3 1	270
	21st to end	Day	31% 13% 32% 18% 5%	297
February	1st to 10th	Day	26% 14% 39% 15% 5%	270
	11th to 20th	Day	27% 16% 36% 17% 4	270
	21st to end	Day	22% 22% 39% 13% 4	225
March	1st to 10th	Day	24% 18% 37% 19% 2	270
	11th to 20th	Day	24% 14% 33% 22% 7% 1	374
	21st to end	Day	30% 12% 32% 19% 6% 1	506
April	1st to 10th	Day	22% 15% 33% 20% 9% 2	460
	11th to 20th	Day	20% 17% 32% 19% 10% 3	452
	21st to end	Day	25% 13% 32% 20% 8% 2	460
May	1st to 10th	Day	22% 13% 32% 20% 10% 3	463
	11th to 20th	Day	19% 8% 31% 24% 14% 5%	487
	21st to end	Day	12% 5% 27% 28% 19% 9%	679
June	1st to 10th	Day	11% 10% 25% 29% 20% 5%	680
	11th to 20th	Day	11% 5% 27% 30% 21% 6%	680
	21st to end	Day	13% 6% 29% 26% 18% 7%	680
July	1st to 10th	Day	12% 4 17% 28% 23% 16%	671
	11th to 20th	Day	7% 4 22% 31% 24% 13%	668
	21st to end	Day	10% 4 18% 32% 27% 10%	730
August	1st to 10th	Day	6% 3 15% 28% 31% 16%	486
	11th to 20th	Day	10% 3 21% 28% 26% 12%	479
	21st to end	Day	8% 2 14% 29% 32% 14%	539
September	1st to 10th	Day	10% 6% 17% 28% 28% 10%	490
	11th to 20th	Day	10% 3 14% 28% 29% 16%	490
	21st to end	Day	14% 9% 25% 23% 22% 7%	490
October	1st to 10th	Day	14% 5% 28% 28% 17% 8%	490
	11th to 20th	Day	18% 17% 26% 28% 9% 2	386
	21st to end	Day	27% 14% 35% 20% 3 1	330
November	1st to 10th	Day	12% 14% 33% 27% 10% 4	300
	11th to 20th	Day	25% 18% 31% 18% 8%	300
	21st to end	Day	29% 15% 33% 18% 4	291
December	1st to 10th	Day	20% 19% 37% 16% 9%	270
	11th to 20th	Day	20% 15% 39% 19% 6% 1	270
	21st to end	Day	26% 21% 37% 14% 2	297
January	1st to 10th	Night	23% 17% 34% 21% 5%	950
	11th to 20th	Night	23% 15% 37% 20% 4	950
	21st to end	Night	23% 13% 35% 25% 5%	1041
February	1st to 10th	Night	26% 10% 37% 24% 3	760
	11th to 20th	Night	21% 14% 38% 24% 3	743
	21st to end	Night	28% 15% 36% 19% 2	628
March	1st to 10th	Night	20% 13% 37% 25% 5% 1	760
	11th to 20th	Night	18% 13% 37% 26% 6%	760
	21st to end	Night	25% 10% 34% 25% 5%	734
April	1st to 10th	Night	18% 12% 39% 23% 6% 1	570
	11th to 20th	Night	24% 9% 33% 25% 7% 1	563
	21st to end	Night	23% 9% 33% 25% 10% 1	570
May	1st to 10th	Night	22% 7% 30% 32% 9% 1	570
	11th to 20th	Night	19% 7% 25% 34% 14% 1	561
	21st to end	Night	12% 5% 23% 40% 19% 1	617
June	1st to 10th	Night	12% 2 24% 45% 16%	570
	11th to 20th	Night	11% 3 27% 40% 19%	570
	21st to end	Night	10% 2 26% 37% 24% 1	570
July	1st to 10th	Night	7% 3 14% 44% 27% 5%	555
	11th to 20th	Night	10% 3 15% 40% 28% 4	552
	21st to end	Night	6% 2 15% 46% 28% 2	624
August	1st to 10th	Night	8% 1 11% 44% 32% 4	567
	11th to 20th	Night	8% 2 13% 44% 29% 4	564
	21st to end	Night	10% 2 14% 34% 37% 4	627
September	1st to 10th	Night	12% 2 16% 38% 28% 4	570
	11th to 20th	Night	10% 4 15% 37% 30% 4	755
	21st to end	Night	15% 5% 22% 32% 24% 2	760
October	1st to 10th	Night	13% 5% 24% 36% 19% 3	760
	11th to 20th	Night	19% 13% 28% 29% 10%	760
	21st to end	Night	25% 12% 31% 25% 7%	836
November	1st to 10th	Night	17% 12% 36% 25% 11% 1	780
	11th to 20th	Night	22% 16% 32% 23% 7% 1	800
	21st to end	Night	24% 15% 32% 24% 6%	789
December	1st to 10th	Night	24% 14% 35% 23% 4	831
	11th to 20th	Night	25% 12% 34% 24% 5%	950
	21st to end	Night	31% 14% 33% 19% 3	1045

Page generated at 2024-11-25 00:22:19. Version ac07

Copyright © 2024 Attilla Danko.