Cold Spring
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cold Spring clear sky chart from 2005-11-06 to 2025-03-12.

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	12% 9% 3 8% 5% 4 5% 4 6% 7% 37%	109209
	Night	11% 9% 3 9% 5% 4 4 4 5% 7% 38%	109959
Transparency	Day	44% 5% 14% 25% 11% 1	112821
	Night	44% 4 13% 25% 12% 1	114476
Seeing	Day	16% 9% 31% 27% 13% 3	16431
	Night	15% 9% 32% 32% 11% 1	26531

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% 12% 3 13% 10% 5% 6% 4 6% 7% 25%	3194
	11th to 20th	Day	6% 9% 5% 13% 8% 7% 7% 8% 10% 6% 21%	3758
	21st to end	Day	4 13% 8% 14% 6% 5% 5% 3 5% 6% 31%	4488
February	1st to 10th	Day	9% 12% 5% 9% 6% 7% 4 3 5% 6% 33%	1800
	11th to 20th	Day	7% 11% 4 11% 7% 5% 5% 4 7% 6% 34%	1754
	21st to end	Day	8% 11% 4 10% 7% 5% 5% 4 5% 6% 34%	1495
March	1st to 10th	Day	11% 13% 4 9% 6% 4 4 4 5% 6% 35%	3546
	11th to 20th	Day	9% 10% 3 8% 4 4 4 4 5% 8% 41%	3491
	21st to end	Day	21% 13% 4 11% 7% 6% 4 3 4 5% 23%	3814
April	1st to 10th	Day	16% 11% 3 8% 5% 3 3 4 5% 7% 35%	2259
	11th to 20th	Day	18% 14% 5% 7% 5% 4 4 3 4 6% 31%	2344
	21st to end	Day	23% 9% 4 6% 5% 4 5% 3 5% 6% 31%	2470
May	1st to 10th	Day	17% 6% 2 6% 5% 4 4 3 6% 7% 39%	4175
	11th to 20th	Day	13% 7% 2 6% 4 4 4 4 5% 6% 45%	4399
	21st to end	Day	17% 7% 2 6% 4 4 5% 4 6% 9% 35%	4824
June	1st to 10th	Day	11% 6% 2 6% 4 4 5% 3 6% 7% 46%	2694
	11th to 20th	Day	13% 7% 3 8% 5% 4 5% 4 6% 8% 38%	2850
	21st to end	Day	10% 5% 2 6% 5% 4 5% 4 7% 10% 42%	2850
July	1st to 10th	Day	9% 5% 2 7% 5% 6% 6% 5% 7% 10% 39%	4750
	11th to 20th	Day	5% 3 1 4 4 3 4 3 5% 8% 59%	4569
	21st to end	Day	6% 5% 2 5% 4 4 5% 4 7% 9% 49%	4666
August	1st to 10th	Day	12% 6% 2 6% 4 4 5% 4 5% 8% 44%	4104
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 4 7% 10% 41%	4041
	21st to end	Day	11% 6% 2 6% 4 4 4 3 5% 8% 48%	4422
September	1st to 10th	Day	9% 5% 1 5% 4 3 4 3 5% 9% 50%	2280
	11th to 20th	Day	11% 5% 2 5% 5% 4 5% 4 6% 7% 47%	2180
	21st to end	Day	15% 5% 2 6% 4 3 3 4 5% 7% 46%	2043
October	1st to 10th	Day	17% 8% 2 5% 3 4 3 4 6% 7% 41%	1900
	11th to 20th	Day	14% 11% 2 7% 4 4 4 3 4 7% 40%	1900
	21st to end	Day	17% 10% 3 7% 5% 4 3 2 4 7% 37%	2088
November	1st to 10th	Day	15% 10% 3 8% 4 5% 4 4 5% 6% 37%	1591
	11th to 20th	Day	9% 13% 6% 13% 6% 5% 4 3 6% 6% 30%	1600
	21st to end	Day	12% 10% 5% 9% 5% 4 4 4 6% 8% 34%	1600
December	1st to 10th	Day	8% 10% 5% 11% 10% 8% 6% 5% 6% 6% 25%	2610
	11th to 20th	Day	9% 16% 7% 10% 6% 4 4 3 5% 6% 30%	3008
	21st to end	Day	19% 18% 6% 20% 5% 4 3 2 3 4 17%	3652
January	1st to 10th	Night	7% 9% 5% 16% 9% 6% 4 3 5% 6% 30%	6764
	11th to 20th	Night	6% 11% 3 10% 7% 7% 10% 8% 8% 6% 23%	6204
	21st to end	Night	5% 17% 8% 9% 5% 4 5% 4 6% 6% 31%	6490
February	1st to 10th	Night	7% 11% 4 10% 7% 5% 4 5% 6% 7% 35%	2600
	11th to 20th	Night	5% 8% 4 9% 5% 5% 6% 4 6% 8% 39%	2533
	21st to end	Night	11% 11% 3 8% 5% 5% 4 5% 6% 6% 37%	2144
March	1st to 10th	Night	8% 8% 2 7% 4 4 3 3 5% 7% 47%	3536
	11th to 20th	Night	9% 8% 3 8% 5% 4 4 3 6% 7% 43%	3497
	21st to end	Night	24% 13% 3 10% 5% 3 4 3 3 5% 27%	3817
April	1st to 10th	Night	14% 10% 3 6% 5% 4 5% 3 4 7% 39%	1920
	11th to 20th	Night	17% 11% 4 7% 3 3 4 3 5% 5% 37%	1783
	21st to end	Night	19% 10% 3 8% 3 4 4 3 4 6% 37%	1710
May	1st to 10th	Night	15% 8% 3 6% 4 4 4 3 5% 6% 44%	2727
	11th to 20th	Night	15% 4 2 5% 4 5% 4 4 6% 7% 46%	2506
	21st to end	Night	17% 7% 2 5% 4 3 4 4 6% 7% 41%	2743
June	1st to 10th	Night	10% 5% 2 4 4 4 5% 5% 7% 9% 47%	1480
	11th to 20th	Night	9% 5% 2 5% 4 4 5% 4 6% 9% 47%	1330
	21st to end	Night	8% 5% 1 5% 4 3 4 4 5% 8% 53%	1330
July	1st to 10th	Night	11% 4 1 4 4 3 5% 4 8% 9% 46%	2220
	11th to 20th	Night	4 3 1 3 3 3 3 3 6% 7% 64%	2398
	21st to end	Night	6% 3 1 5% 3 3 4 4 6% 8% 58%	2894
August	1st to 10th	Night	11% 6% 2 5% 3 3 4 3 5% 7% 50%	2836
	11th to 20th	Night	14% 4 2 5% 4 4 4 4 6% 7% 48%	2798
	21st to end	Night	10% 5% 2 6% 3 3 4 3 5% 8% 49%	3228
September	1st to 10th	Night	8% 3 2 5% 3 3 4 3 6% 7% 57%	1900
	11th to 20th	Night	9% 5% 2 5% 3 4 4 3 4 7% 54%	1995
	21st to end	Night	12% 5% 2 5% 3 3 3 3 5% 6% 53%	2118
October	1st to 10th	Night	14% 6% 2 5% 3 3 3 4 5% 6% 49%	2280
	11th to 20th	Night	15% 8% 3 5% 4 4 4 3 5% 7% 44%	2280
	21st to end	Night	17% 9% 3 8% 4 4 4 3 4 7% 38%	2508
November	1st to 10th	Night	12% 9% 3 6% 4 4 5% 3 6% 7% 40%	2707
	11th to 20th	Night	12% 12% 5% 10% 5% 5% 4 3 4 5% 35%	2800
	21st to end	Night	12% 9% 3 9% 5% 4 4 3 5% 7% 39%	2800
December	1st to 10th	Night	6% 7% 4 12% 9% 7% 6% 4 6% 8% 31%	4580
	11th to 20th	Night	10% 14% 6% 13% 8% 5% 4 4 5% 5% 26%	5199
	21st to end	Night	19% 17% 6% 16% 5% 4 4 3 3 4 18%	7304

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	57% 4 11% 16% 11%	3195
	11th to 20th	Day	56% 4 12% 19% 9%	3758
	21st to end	Day	55% 4 16% 16% 9%	4488
February	1st to 10th	Day	52% 4 12% 22% 9% 1	1800
	11th to 20th	Day	49% 5% 13% 24% 8% 1	1763
	21st to end	Day	51% 4 12% 21% 11% 1	1495
March	1st to 10th	Day	48% 5% 13% 24% 9% 1	3546
	11th to 20th	Day	41% 5% 12% 31% 10% 1	3491
	21st to end	Day	64% 5% 9% 17% 5%	3814
April	1st to 10th	Day	48% 4 11% 22% 13% 2	2259
	11th to 20th	Day	55% 4 9% 19% 11% 1	2344
	21st to end	Day	53% 5% 11% 20% 9% 1	2470
May	1st to 10th	Day	42% 6% 12% 24% 14% 1	4213
	11th to 20th	Day	38% 5% 11% 31% 13% 2	4403
	21st to end	Day	44% 7% 13% 27% 8% 1	4837
June	1st to 10th	Day	36% 5% 15% 30% 12% 1	2694
	11th to 20th	Day	43% 6% 14% 21% 14% 1	2850
	21st to end	Day	36% 6% 18% 27% 11% 2	2850
July	1st to 10th	Day	37% 8% 20% 22% 13%	4676
	11th to 20th	Day	22% 5% 18% 37% 16% 2	4489
	21st to end	Day	29% 7% 16% 32% 14% 1	4519
August	1st to 10th	Day	38% 4 13% 31% 12% 2	4090
	11th to 20th	Day	38% 6% 14% 32% 9%	4080
	21st to end	Day	34% 6% 17% 30% 12% 1	4421
September	1st to 10th	Day	30% 5% 15% 37% 12%	2280
	11th to 20th	Day	35% 6% 19% 30% 10% 1	2180
	21st to end	Day	38% 5% 12% 33% 11% 1	2043
October	1st to 10th	Day	32% 3 10% 33% 22% 1	3160
	11th to 20th	Day	38% 4 13% 22% 21% 2	3140
	21st to end	Day	46% 3 15% 28% 9%	3415
November	1st to 10th	Day	48% 5% 12% 20% 13% 3	1591
	11th to 20th	Day	55% 4 13% 19% 9% 1	1600
	21st to end	Day	49% 5% 15% 22% 7% 2	1600
December	1st to 10th	Day	58% 6% 14% 16% 4 1	2610
	11th to 20th	Day	57% 3 14% 19% 7%	3005
	21st to end	Day	72% 3 8% 11% 5%	3652
January	1st to 10th	Night	56% 3 11% 20% 10%	6764
	11th to 20th	Night	57% 4 11% 15% 11% 1	6204
	21st to end	Night	53% 4 12% 24% 6%	6490
February	1st to 10th	Night	47% 4 14% 22% 12% 2	2600
	11th to 20th	Night	42% 5% 14% 25% 12% 1	2534
	21st to end	Night	46% 5% 13% 21% 13% 2	2144
March	1st to 10th	Night	36% 5% 13% 28% 16% 2	3536
	11th to 20th	Night	38% 5% 11% 30% 15%	3497
	21st to end	Night	60% 4 7% 21% 6% 1	3817
April	1st to 10th	Night	46% 5% 10% 26% 13% 1	1920
	11th to 20th	Night	48% 4 7% 23% 16% 2	1783
	21st to end	Night	49% 5% 9% 22% 13% 2	1710
May	1st to 10th	Night	40% 6% 11% 25% 15% 3	2754
	11th to 20th	Night	36% 6% 10% 24% 20% 3	2507
	21st to end	Night	40% 6% 13% 25% 14% 1	2751
June	1st to 10th	Night	31% 6% 16% 30% 14% 2	1480
	11th to 20th	Night	32% 6% 17% 26% 16% 3	1330
	21st to end	Night	30% 5% 15% 29% 17% 3	1330
July	1st to 10th	Night	32% 7% 23% 22% 16% 1	2185
	11th to 20th	Night	18% 5% 14% 40% 19% 3	2355
	21st to end	Night	23% 6% 17% 35% 15% 3	2802
August	1st to 10th	Night	34% 4 14% 29% 14% 5%	2826
	11th to 20th	Night	35% 5% 15% 33% 12%	2825
	21st to end	Night	32% 6% 18% 30% 12% 2	3228
September	1st to 10th	Night	26% 5% 17% 35% 17% 1	1900
	11th to 20th	Night	30% 4 17% 32% 17%	1995
	21st to end	Night	32% 4 12% 34% 17% 1	2118
October	1st to 10th	Night	24% 3 7% 37% 25% 4	3800
	11th to 20th	Night	33% 3 12% 27% 22% 2	3779
	21st to end	Night	42% 4 14% 27% 12%	4120
November	1st to 10th	Night	42% 5% 14% 26% 13% 2	2707
	11th to 20th	Night	51% 4 13% 19% 12% 1	2800
	21st to end	Night	46% 4 17% 24% 7% 2	2800
December	1st to 10th	Night	51% 5% 18% 20% 6%	4580
	11th to 20th	Night	60% 4 11% 19% 6% 1	5201
	21st to end	Night	71% 3 8% 14% 4	7304

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% 9% 32% 30% 12% 2	300
	11th to 20th	Day	17% 8% 40% 30% 5%	300
	21st to end	Day	13% 10% 41% 21% 13% 2	330
February	1st to 10th	Day	16% 15% 45% 21% 3	300
	11th to 20th	Day	12% 20% 36% 23% 9%	300
	21st to end	Day	16% 12% 42% 27% 3	249
March	1st to 10th	Day	21% 11% 40% 22% 5% 1	300
	11th to 20th	Day	20% 8% 39% 22% 9% 1	273
	21st to end	Day	25% 11% 28% 24% 9% 2	297
April	1st to 10th	Day	27% 13% 30% 23% 6%	439
	11th to 20th	Day	28% 13% 26% 23% 9% 1	542
	21st to end	Day	25% 8% 36% 20% 9% 2	650
May	1st to 10th	Day	23% 10% 34% 24% 8% 2	653
	11th to 20th	Day	18% 10% 30% 26% 12% 3	675
	21st to end	Day	18% 6% 28% 32% 13% 2	734
June	1st to 10th	Day	11% 8% 25% 31% 20% 4	680
	11th to 20th	Day	16% 6% 35% 29% 13% 1	680
	21st to end	Day	13% 7% 32% 27% 17% 5%	680
July	1st to 10th	Day	7% 5% 22% 33% 23% 9%	671
	11th to 20th	Day	9% 6% 28% 29% 19% 8%	668
	21st to end	Day	7% 4 26% 35% 22% 6%	739
August	1st to 10th	Day	11% 4 22% 32% 26% 5%	676
	11th to 20th	Day	12% 5% 21% 34% 23% 6%	665
	21st to end	Day	11% 6% 24% 34% 21% 4	690
September	1st to 10th	Day	12% 6% 29% 33% 16% 4	490
	11th to 20th	Day	10% 3 30% 33% 18% 5%	390
	21st to end	Day	22% 10% 28% 21% 14% 5%	300
October	1st to 10th	Day	18% 12% 30% 23% 12% 5%	300
	11th to 20th	Day	16% 15% 37% 22% 8% 2	300
	21st to end	Day	23% 15% 37% 18% 6% 1	330
November	1st to 10th	Day	23% 12% 30% 26% 8% 2	300
	11th to 20th	Day	19% 17% 40% 20% 4	300
	21st to end	Day	19% 15% 37% 24% 5%	300
December	1st to 10th	Day	15% 9% 42% 25% 9%	300
	11th to 20th	Day	19% 13% 39% 25% 3	300
	21st to end	Day	31% 10% 35% 20% 3 1	330
January	1st to 10th	Night	11% 11% 37% 31% 8% 2	1000
	11th to 20th	Night	16% 11% 37% 29% 7% 1	1000
	21st to end	Night	16% 12% 37% 27% 9%	1100
February	1st to 10th	Night	12% 11% 39% 29% 8% 1	1000
	11th to 20th	Night	10% 12% 42% 28% 7% 1	979
	21st to end	Night	15% 11% 33% 31% 7% 1	824
March	1st to 10th	Night	15% 10% 37% 29% 9% 1	607
	11th to 20th	Night	16% 10% 41% 26% 6% 1	575
	21st to end	Night	23% 8% 31% 26% 10% 2	627
April	1st to 10th	Night	19% 8% 39% 27% 6%	570
	11th to 20th	Night	23% 12% 29% 28% 9% 1	563
	21st to end	Night	23% 8% 30% 30% 8% 2	570
May	1st to 10th	Night	19% 8% 33% 29% 10% 1	570
	11th to 20th	Night	16% 7% 31% 34% 11% 1	561
	21st to end	Night	16% 6% 27% 36% 14% 1	617
June	1st to 10th	Night	14% 4 27% 37% 17% 1	570
	11th to 20th	Night	12% 3 32% 44% 10%	570
	21st to end	Night	10% 4 28% 41% 17% 1	570
July	1st to 10th	Night	5% 2 22% 42% 27% 2	555
	11th to 20th	Night	7% 2 25% 47% 17% 2	552
	21st to end	Night	6% 1 22% 46% 22% 2	624
August	1st to 10th	Night	9% 2 18% 49% 21% 2	567
	11th to 20th	Night	12% 2 18% 40% 26% 3	564
	21st to end	Night	9% 3 24% 39% 23% 2	627
September	1st to 10th	Night	10% 4 25% 41% 18% 2	570
	11th to 20th	Night	11% 6% 29% 32% 21% 1	570
	21st to end	Night	14% 8% 32% 31% 13% 2	598
October	1st to 10th	Night	15% 9% 32% 31% 11% 1	760
	11th to 20th	Night	20% 9% 35% 30% 6% 1	760
	21st to end	Night	22% 11% 32% 28% 7%	836
November	1st to 10th	Night	17% 10% 32% 32% 9% 1	975
	11th to 20th	Night	18% 12% 35% 27% 8% 1	1000
	21st to end	Night	17% 14% 36% 26% 8%	1000
December	1st to 10th	Night	15% 11% 37% 29% 8% 1	1000
	11th to 20th	Night	21% 9% 35% 28% 5% 1	1000
	21st to end	Night	25% 10% 33% 26% 6% 1	1100

Page generated at 2025-03-09 07:08:49. Version ac07

Copyright © 2025 Attilla Danko.