Mark's place
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mark's place clear sky chart from 2005-11-06 to 2024-11-05.

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	13% 9% 3 8% 5% 4 4 4 6% 7% 38%	101495
	Night	13% 9% 3 8% 5% 4 4 3 5% 6% 39%	97626
Transparency	Day	43% 6% 12% 24% 13% 1	105023
	Night	44% 6% 11% 23% 14% 2	102238
Seeing	Day	16% 11% 29% 25% 14% 5%	15895
	Night	17% 9% 31% 30% 11% 1	25733

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	11% 14% 10% 15% 5% 5% 3 2 4 5% 27%	2527
	11th to 20th	Day	10% 11% 5% 14% 6% 5% 5% 9% 8% 7% 20%	2530
	21st to end	Day	15% 21% 8% 12% 4 3 4 3 4 5% 21%	2980
February	1st to 10th	Day	12% 13% 5% 8% 5% 5% 4 4 5% 7% 32%	1710
	11th to 20th	Day	13% 11% 4 6% 5% 4 5% 3 5% 7% 36%	1762
	21st to end	Day	12% 14% 4 10% 6% 4 3 3 5% 6% 33%	1570
March	1st to 10th	Day	14% 9% 3 7% 4 3 4 3 4 6% 44%	3120
	11th to 20th	Day	11% 7% 2 9% 4 4 3 4 6% 6% 44%	3415
	21st to end	Day	22% 13% 3 9% 5% 4 4 3 5% 6% 26%	4085
April	1st to 10th	Day	18% 12% 4 7% 5% 5% 5% 3 5% 5% 31%	2280
	11th to 20th	Day	17% 11% 3 7% 6% 4 4 3 5% 5% 34%	2254
	21st to end	Day	18% 10% 3 7% 5% 5% 4 3 6% 6% 33%	2308
May	1st to 10th	Day	15% 7% 3 8% 5% 5% 4 3 6% 7% 36%	4266
	11th to 20th	Day	13% 7% 3 6% 5% 4 4 4 5% 7% 42%	4399
	21st to end	Day	13% 7% 2 7% 5% 5% 4 4 6% 8% 38%	4824
June	1st to 10th	Day	11% 4 2 5% 5% 4 5% 5% 7% 8% 43%	2660
	11th to 20th	Day	12% 5% 2 6% 5% 4 4 5% 6% 9% 42%	2660
	21st to end	Day	11% 7% 2 7% 5% 5% 5% 4 7% 8% 38%	2660
July	1st to 10th	Day	10% 7% 3 7% 5% 5% 6% 5% 8% 9% 34%	4440
	11th to 20th	Day	5% 4 2 5% 4 5% 4 5% 7% 10% 50%	4440
	21st to end	Day	8% 6% 3 7% 6% 5% 5% 5% 6% 9% 40%	4813
August	1st to 10th	Day	9% 5% 3 6% 5% 5% 6% 4 7% 9% 40%	4275
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 6% 8% 46%	3851
	21st to end	Day	9% 6% 3 6% 4 4 4 4 6% 10% 45%	4180
September	1st to 10th	Day	12% 6% 2 7% 4 5% 4 4 6% 7% 45%	2280
	11th to 20th	Day	11% 5% 2 5% 3 3 3 3 5% 9% 50%	2240
	21st to end	Day	12% 8% 2 6% 5% 4 4 3 5% 7% 44%	2090
October	1st to 10th	Day	12% 7% 2 7% 4 3 3 3 5% 6% 48%	1906
	11th to 20th	Day	18% 9% 2 7% 4 4 3 4 5% 6% 38%	1900
	21st to end	Day	18% 9% 3 7% 4 3 3 3 4 5% 40%	1944
November	1st to 10th	Day	11% 8% 2 7% 5% 5% 4 4 5% 5% 44%	1708
	11th to 20th	Day	14% 12% 3 8% 5% 6% 4 3 5% 6% 34%	1677
	21st to end	Day	14% 12% 3 8% 5% 3 3 3 4 6% 37%	1520
December	1st to 10th	Day	14% 14% 4 10% 5% 4 4 4 5% 5% 32%	1520
	11th to 20th	Day	13% 13% 5% 9% 6% 4 5% 4 5% 7% 28%	1918
	21st to end	Day	19% 22% 8% 10% 5% 4 4 4 4 4 16%	2783
January	1st to 10th	Night	11% 13% 7% 12% 6% 4 4 3 4 5% 30%	4428
	11th to 20th	Night	11% 15% 7% 14% 6% 5% 4 5% 8% 5% 21%	4440
	21st to end	Night	16% 18% 7% 12% 5% 5% 4 3 4 4 22%	4683
February	1st to 10th	Night	11% 12% 5% 9% 5% 6% 4 4 5% 5% 33%	2470
	11th to 20th	Night	10% 10% 3 8% 6% 5% 4 4 4 6% 40%	2303
	21st to end	Night	15% 12% 4 8% 4 4 2 3 5% 6% 36%	1884
March	1st to 10th	Night	17% 10% 3 6% 4 4 4 3 4 5% 41%	3733
	11th to 20th	Night	10% 6% 2 6% 4 4 4 3 6% 8% 47%	3561
	21st to end	Night	24% 12% 4 11% 5% 4 3 3 4 5% 26%	3545
April	1st to 10th	Night	17% 9% 3 6% 5% 4 4 3 5% 6% 38%	1900
	11th to 20th	Night	19% 9% 3 6% 4 4 4 3 5% 7% 37%	1875
	21st to end	Night	16% 9% 2 6% 5% 4 5% 4 5% 8% 37%	1872
May	1st to 10th	Night	17% 8% 3 6% 4 5% 4 4 5% 7% 36%	2632
	11th to 20th	Night	11% 8% 3 7% 5% 4 4 3 6% 6% 42%	2506
	21st to end	Night	9% 7% 2 6% 3 5% 4 4 6% 9% 45%	2743
June	1st to 10th	Night	9% 4 2 5% 5% 4 5% 4 7% 10% 45%	1520
	11th to 20th	Night	11% 6% 2 5% 4 4 4 4 7% 9% 45%	1520
	21st to end	Night	9% 5% 3 6% 4 4 3 4 6% 7% 49%	1520
July	1st to 10th	Night	13% 7% 2 7% 3 4 4 4 6% 8% 42%	2530
	11th to 20th	Night	4 3 1 5% 4 4 4 4 6% 9% 56%	2530
	21st to end	Night	5% 4 2 5% 5% 4 5% 4 6% 9% 49%	2750
August	1st to 10th	Night	8% 4 2 5% 4 4 4 4 6% 7% 50%	2662
	11th to 20th	Night	9% 5% 2 5% 3 4 4 3 6% 7% 51%	2980
	21st to end	Night	10% 5% 2 6% 4 4 4 4 5% 7% 50%	3476
September	1st to 10th	Night	7% 5% 2 5% 4 3 3 3 6% 6% 56%	1900
	11th to 20th	Night	10% 5% 1 5% 3 3 5% 4 5% 7% 52%	1920
	21st to end	Night	9% 5% 2 5% 3 4 5% 3 5% 7% 51%	2090
October	1st to 10th	Night	11% 5% 2 5% 4 3 3 3 5% 6% 52%	2270
	11th to 20th	Night	16% 7% 2 5% 4 4 4 3 5% 6% 44%	2280
	21st to end	Night	17% 9% 3 7% 4 4 4 3 5% 7% 37%	2652
November	1st to 10th	Night	12% 8% 3 6% 4 3 2 3 5% 5% 49%	2470
	11th to 20th	Night	14% 11% 3 9% 5% 4 4 4 5% 6% 35%	2498
	21st to end	Night	17% 10% 3 7% 4 4 3 3 4 6% 39%	2660
December	1st to 10th	Night	14% 12% 4 10% 5% 4 6% 4 5% 6% 30%	2660
	11th to 20th	Night	15% 13% 5% 9% 6% 5% 5% 4 5% 5% 29%	3279
	21st to end	Night	20% 17% 6% 11% 6% 5% 4 3 4 5% 19%	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	61% 5% 12% 16% 7%	2528
	11th to 20th	Day	57% 7% 14% 14% 8% 1	2530
	21st to end	Day	66% 4 10% 14% 5%	2980
February	1st to 10th	Day	53% 5% 12% 19% 11% 1	1710
	11th to 20th	Day	48% 5% 12% 24% 10% 2	1771
	21st to end	Day	52% 5% 10% 20% 10% 2	1570
March	1st to 10th	Day	41% 6% 11% 28% 11% 3	3120
	11th to 20th	Day	38% 7% 11% 31% 12% 1	3415
	21st to end	Day	59% 7% 11% 16% 6% 1	4085
April	1st to 10th	Day	53% 5% 10% 20% 10%	2280
	11th to 20th	Day	50% 6% 9% 21% 12% 2	2254
	21st to end	Day	50% 7% 10% 19% 12% 1	2308
May	1st to 10th	Day	45% 6% 11% 21% 15% 1	4304
	11th to 20th	Day	40% 8% 10% 30% 12%	4403
	21st to end	Day	40% 9% 11% 23% 15% 3	4837
June	1st to 10th	Day	36% 8% 15% 25% 15% 1	2660
	11th to 20th	Day	36% 9% 13% 22% 18% 2	2660
	21st to end	Day	41% 8% 14% 23% 13% 2	2660
July	1st to 10th	Day	42% 9% 14% 25% 8% 1	4371
	11th to 20th	Day	27% 8% 16% 32% 16% 1	4365
	21st to end	Day	39% 8% 14% 19% 17% 2	4662
August	1st to 10th	Day	38% 8% 15% 25% 12% 1	4260
	11th to 20th	Day	34% 6% 14% 31% 14% 1	3890
	21st to end	Day	34% 5% 14% 31% 15% 1	4179
September	1st to 10th	Day	37% 8% 10% 25% 19% 2	2280
	11th to 20th	Day	31% 6% 13% 32% 17% 2	2240
	21st to end	Day	39% 5% 10% 28% 17% 1	2090
October	1st to 10th	Day	23% 4 6% 39% 27% 1	3166
	11th to 20th	Day	34% 4 9% 26% 24% 2	3140
	21st to end	Day	41% 4 10% 27% 14% 3	3182
November	1st to 10th	Day	41% 5% 13% 25% 13% 2	1708
	11th to 20th	Day	50% 6% 13% 21% 10% 1	1677
	21st to end	Day	49% 5% 16% 22% 7% 1	1520
December	1st to 10th	Day	53% 5% 13% 18% 8% 2	1520
	11th to 20th	Day	54% 5% 15% 15% 8% 2	1915
	21st to end	Day	71% 6% 9% 9% 5%	2783
January	1st to 10th	Night	56% 6% 10% 19% 8% 1	4428
	11th to 20th	Night	61% 5% 11% 14% 8%	4440
	21st to end	Night	65% 5% 8% 15% 5% 1	4683
February	1st to 10th	Night	53% 5% 11% 17% 12% 2	2470
	11th to 20th	Night	46% 5% 11% 22% 14% 1	2304
	21st to end	Night	50% 4 12% 20% 10% 3	1884
March	1st to 10th	Night	47% 5% 11% 23% 10% 5%	3733
	11th to 20th	Night	33% 6% 12% 31% 17% 2	3561
	21st to end	Night	61% 5% 7% 17% 9% 1	3545
April	1st to 10th	Night	46% 7% 11% 22% 14% 2	1900
	11th to 20th	Night	48% 4 7% 18% 19% 3	1875
	21st to end	Night	44% 8% 12% 22% 12% 2	1872
May	1st to 10th	Night	46% 7% 12% 15% 19% 1	2659
	11th to 20th	Night	40% 8% 11% 24% 16% 1	2507
	21st to end	Night	32% 10% 13% 23% 20% 3	2751
June	1st to 10th	Night	32% 8% 14% 26% 19% 1	1520
	11th to 20th	Night	34% 6% 11% 24% 22% 3	1520
	21st to end	Night	34% 8% 16% 22% 18% 3	1520
July	1st to 10th	Night	40% 6% 16% 24% 12% 3	2490
	11th to 20th	Night	24% 8% 14% 34% 18% 2	2482
	21st to end	Night	29% 9% 17% 21% 19% 5%	2662
August	1st to 10th	Night	31% 7% 13% 29% 19% 1	2653
	11th to 20th	Night	31% 7% 12% 32% 17% 1	3007
	21st to end	Night	33% 5% 12% 28% 18% 4	3476
September	1st to 10th	Night	27% 7% 12% 27% 24% 2	1900
	11th to 20th	Night	31% 6% 12% 31% 19% 2	1920
	21st to end	Night	32% 6% 10% 30% 20% 2	2090
October	1st to 10th	Night	24% 4 6% 37% 28% 2	3790
	11th to 20th	Night	32% 4 10% 27% 25% 3	3779
	21st to end	Night	43% 4 9% 26% 15% 2	4364
November	1st to 10th	Night	39% 5% 11% 26% 17% 3	2470
	11th to 20th	Night	49% 5% 13% 19% 12% 1	2498
	21st to end	Night	47% 5% 13% 24% 11% 1	2660
December	1st to 10th	Night	54% 5% 12% 20% 8% 1	2660
	11th to 20th	Night	55% 6% 12% 18% 7% 1	3281
	21st to end	Night	67% 5% 9% 14% 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	19% 14% 30% 27% 8% 2	270
	11th to 20th	Day	20% 15% 40% 19% 5% 1	270
	21st to end	Day	22% 14% 36% 22% 5%	297
February	1st to 10th	Day	15% 21% 37% 20% 6% 1	270
	11th to 20th	Day	22% 20% 33% 21% 4	270
	21st to end	Day	22% 19% 43% 16% 1	225
March	1st to 10th	Day	16% 19% 43% 18% 4	270
	11th to 20th	Day	19% 23% 35% 14% 6% 3	270
	21st to end	Day	27% 14% 32% 19% 6% 2	452
April	1st to 10th	Day	26% 16% 32% 21% 5%	460
	11th to 20th	Day	27% 15% 27% 19% 11% 2	452
	21st to end	Day	22% 11% 30% 25% 9% 2	460
May	1st to 10th	Day	20% 11% 33% 25% 9% 2	569
	11th to 20th	Day	19% 12% 30% 24% 11% 4	675
	21st to end	Day	16% 10% 26% 25% 16% 7%	734
June	1st to 10th	Day	11% 6% 29% 29% 19% 5%	680
	11th to 20th	Day	12% 7% 32% 30% 15% 4	680
	21st to end	Day	13% 8% 29% 30% 16% 4	680
July	1st to 10th	Day	8% 4 20% 28% 28% 13%	671
	11th to 20th	Day	9% 5% 26% 29% 22% 9%	668
	21st to end	Day	9% 3 26% 33% 22% 8%	739
August	1st to 10th	Day	7% 3 20% 37% 23% 9%	676
	11th to 20th	Day	14% 5% 20% 27% 22% 13%	553
	21st to end	Day	10% 7% 19% 32% 22% 9%	539
September	1st to 10th	Day	14% 7% 22% 30% 19% 8%	490
	11th to 20th	Day	12% 3 21% 29% 26% 9%	490
	21st to end	Day	15% 10% 27% 26% 17% 5%	490
October	1st to 10th	Day	16% 11% 28% 27% 14% 3	306
	11th to 20th	Day	23% 16% 34% 18% 9%	300
	21st to end	Day	27% 16% 29% 22% 5% 2	330
November	1st to 10th	Day	16% 14% 39% 20% 9% 2	282
	11th to 20th	Day	17% 20% 37% 17% 8%	270
	21st to end	Day	21% 14% 38% 22% 4	270
December	1st to 10th	Day	19% 18% 39% 17% 7% 1	270
	11th to 20th	Day	19% 13% 39% 21% 9%	270
	21st to end	Day	25% 18% 38% 17% 1	297
January	1st to 10th	Night	16% 15% 37% 23% 7% 1	950
	11th to 20th	Night	19% 13% 39% 23% 5% 1	950
	21st to end	Night	22% 11% 36% 26% 6%	1045
February	1st to 10th	Night	18% 12% 39% 25% 6%	950
	11th to 20th	Night	16% 15% 38% 26% 4	829
	21st to end	Night	23% 14% 40% 19% 4	628
March	1st to 10th	Night	22% 13% 37% 22% 5%	760
	11th to 20th	Night	17% 10% 35% 29% 8%	625
	21st to end	Night	24% 11% 34% 26% 6% 1	627
April	1st to 10th	Night	20% 15% 37% 24% 5%	570
	11th to 20th	Night	22% 15% 29% 28% 7%	563
	21st to end	Night	19% 9% 34% 28% 9% 1	570
May	1st to 10th	Night	17% 9% 36% 29% 8% 1	570
	11th to 20th	Night	18% 6% 32% 33% 11% 1	561
	21st to end	Night	14% 3 29% 37% 16% 1	617
June	1st to 10th	Night	10% 5% 26% 45% 13% 1	570
	11th to 20th	Night	13% 4 30% 39% 13%	570
	21st to end	Night	11% 4 26% 41% 17% 1	570
July	1st to 10th	Night	9% 2 14% 39% 32% 4	555
	11th to 20th	Night	7% 3 22% 41% 23% 3	552
	21st to end	Night	7% 1 18% 46% 25% 2	624
August	1st to 10th	Night	6% 3 16% 44% 29% 3	567
	11th to 20th	Night	12% 2 14% 39% 28% 5%	564
	21st to end	Night	10% 2 16% 43% 26% 3	627
September	1st to 10th	Night	9% 3 22% 39% 22% 5%	570
	11th to 20th	Night	11% 4 21% 34% 25% 4	590
	21st to end	Night	11% 7% 26% 36% 18% 2	760
October	1st to 10th	Night	16% 6% 26% 33% 18% 1	760
	11th to 20th	Night	18% 12% 30% 30% 9%	760
	21st to end	Night	21% 11% 33% 27% 7%	836
November	1st to 10th	Night	17% 9% 38% 25% 9% 1	760
	11th to 20th	Night	19% 14% 37% 23% 6% 1	788
	21st to end	Night	22% 12% 35% 23% 7%	950
December	1st to 10th	Night	21% 12% 37% 24% 5%	950
	11th to 20th	Night	23% 10% 36% 24% 5% 1	950
	21st to end	Night	27% 14% 34% 22% 2	1045

Page generated at 2024-11-03 01:11:11. Version ac07

Copyright © 2024 Attilla Danko.