Hastings
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hastings clear sky chart from 2005-11-06 to 2026-09-29.

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%	158455
	Night	8% 6% 2 6% 4 4 4 3 5% 7% 52%	150357
Transparency	Day	33% 6% 13% 26% 19% 4	153192
	Night	32% 5% 13% 26% 20% 4	146632
Seeing	Day	13% 10% 32% 30% 14% 2	18406
	Night	11% 9% 36% 34% 9% 1	28184

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	9% 12% 4 10% 5% 4 4 3 4 5% 40%	4720
	11th to 20th	Day	4 9% 3 8% 5% 5% 4 4 5% 7% 45%	5288
	21st to end	Day	5% 10% 4 11% 4 4 4 3 4 5% 46%	5812
February	1st to 10th	Day	9% 11% 4 8% 5% 4 4 3 6% 7% 40%	1890
	11th to 20th	Day	6% 8% 3 7% 4 4 4 3 6% 8% 47%	2044
	21st to end	Day	8% 6% 2 6% 4 3 4 3 5% 6% 54%	1730
March	1st to 10th	Day	11% 8% 2 5% 3 3 2 2 3 4 57%	4735
	11th to 20th	Day	9% 7% 2 5% 3 3 3 2 4 7% 55%	5090
	21st to end	Day	13% 9% 3 6% 4 4 4 3 5% 8% 42%	5585
April	1st to 10th	Day	11% 7% 3 5% 4 3 5% 3 5% 6% 48%	2389
	11th to 20th	Day	13% 7% 2 6% 5% 4 3 3 6% 7% 45%	2633
	21st to end	Day	18% 7% 2 6% 4 3 4 3 5% 7% 41%	2730
May	1st to 10th	Day	11% 6% 2 5% 3 4 4 4 6% 7% 48%	7655
	11th to 20th	Day	11% 5% 2 5% 3 3 3 3 4 6% 53%	7627
	21st to end	Day	17% 7% 2 6% 4 4 4 3 5% 6% 41%	8404
June	1st to 10th	Day	6% 4 2 5% 4 4 5% 4 6% 8% 53%	2730
	11th to 20th	Day	8% 4 2 4 4 3 4 4 6% 8% 52%	2935
	21st to end	Day	8% 4 1 5% 4 4 4 3 7% 9% 52%	2940
July	1st to 10th	Day	6% 5% 2 6% 4 4 4 4 6% 8% 51%	8249
	11th to 20th	Day	5% 3 1 4 3 4 4 3 5% 7% 60%	7917
	21st to end	Day	8% 6% 2 6% 4 4 5% 4 7% 9% 45%	8339
August	1st to 10th	Day	8% 4 2 6% 4 4 4 4 6% 9% 49%	7581
	11th to 20th	Day	9% 5% 2 6% 4 4 5% 4 7% 9% 45%	7598
	21st to end	Day	11% 5% 2 7% 5% 4 4 4 5% 7% 47%	8177
September	1st to 10th	Day	11% 5% 2 5% 4 4 4 2 4 6% 55%	2370
	11th to 20th	Day	10% 5% 2 5% 4 3 3 3 5% 7% 54%	2310
	21st to end	Day	10% 4 1 4 3 3 3 3 4 7% 58%	2288
October	1st to 10th	Day	9% 3 1 3 2 2 2 2 3 4 70%	3524
	11th to 20th	Day	6% 4 1 3 2 2 3 3 4 7% 65%	3240
	21st to end	Day	10% 5% 2 5% 2 2 3 2 4 6% 57%	3357
November	1st to 10th	Day	8% 5% 1 4 2 4 4 2 6% 7% 57%	1853
	11th to 20th	Day	6% 7% 2 5% 3 3 2 3 5% 5% 57%	1890
	21st to end	Day	9% 8% 3 5% 3 3 3 3 4 6% 51%	1890
December	1st to 10th	Day	4 5% 2 6% 4 4 4 3 5% 7% 57%	3030
	11th to 20th	Day	6% 7% 3 8% 5% 4 4 3 5% 6% 51%	3481
	21st to end	Day	12% 10% 3 11% 5% 4 4 3 5% 5% 38%	4424
January	1st to 10th	Night	7% 11% 4 11% 4 4 4 3 5% 6% 40%	8187
	11th to 20th	Night	3 6% 2 7% 5% 5% 5% 3 5% 7% 51%	7680
	21st to end	Night	6% 9% 4 10% 4 4 4 3 4 5% 47%	8402
February	1st to 10th	Night	8% 10% 3 6% 5% 4 4 4 5% 5% 44%	2730
	11th to 20th	Night	6% 8% 3 7% 5% 4 4 4 6% 7% 46%	2481
	21st to end	Night	6% 7% 2 6% 4 4 3 3 4 6% 55%	2076
March	1st to 10th	Night	9% 5% 2 5% 3 4 3 3 5% 5% 56%	5353
	11th to 20th	Night	9% 5% 2 4 3 3 3 3 4 6% 59%	5090
	21st to end	Night	11% 7% 3 6% 4 5% 5% 4 6% 7% 41%	5588
April	1st to 10th	Night	11% 6% 2 5% 4 4 4 3 5% 7% 48%	2226
	11th to 20th	Night	12% 6% 2 4 4 4 4 3 5% 9% 47%	1934
	21st to end	Night	13% 6% 3 6% 3 3 3 3 4 9% 49%	1890
May	1st to 10th	Night	15% 6% 2 4 3 3 3 3 5% 6% 49%	5292
	11th to 20th	Night	9% 5% 1 4 3 4 4 3 5% 8% 54%	5265
	21st to end	Night	17% 7% 2 6% 4 4 4 3 5% 7% 42%	5803
June	1st to 10th	Night	6% 4 1 5% 3 3 4 4 7% 9% 54%	1889
	11th to 20th	Night	8% 4 2 4 3 3 4 4 6% 8% 56%	1680
	21st to end	Night	5% 3 2 4 3 3 4 4 6% 9% 57%	1680
July	1st to 10th	Night	7% 4 2 5% 4 4 4 4 6% 9% 51%	4740
	11th to 20th	Night	6% 3 1 4 4 3 4 4 6% 8% 57%	5057
	21st to end	Night	7% 5% 2 5% 4 4 4 4 6% 10% 48%	5770
August	1st to 10th	Night	4 4 2 5% 3 3 4 3 6% 11% 56%	5241
	11th to 20th	Night	7% 4 2 5% 3 3 5% 4 7% 10% 49%	5258
	21st to end	Night	8% 5% 2 6% 4 5% 5% 4 7% 10% 44%	6023
September	1st to 10th	Night	8% 4 1 3 2 3 3 3 5% 7% 62%	2248
	11th to 20th	Night	8% 5% 2 4 3 4 4 3 5% 6% 57%	2310
	21st to end	Night	8% 4 2 4 4 4 3 2 5% 6% 59%	2288
October	1st to 10th	Night	8% 3 1 3 2 2 2 2 3 5% 70%	3621
	11th to 20th	Night	6% 3 1 3 3 3 3 2 4 6% 66%	3899
	21st to end	Night	9% 4 1 4 3 3 3 2 4 7% 59%	4437
November	1st to 10th	Night	6% 4 1 4 3 3 3 2 5% 7% 62%	2665
	11th to 20th	Night	7% 5% 2 4 4 3 3 3 5% 7% 59%	2730
	21st to end	Night	9% 6% 2 4 3 3 3 3 5% 7% 56%	2730
December	1st to 10th	Night	3 5% 1 3 4 2 3 3 5% 7% 64%	4380
	11th to 20th	Night	7% 4 1 5% 3 4 4 3 6% 8% 54%	4946
	21st to end	Night	13% 11% 3 8% 4 4 4 3 4 6% 39%	6768

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	46% 4 11% 23% 14% 2	4723
	11th to 20th	Day	39% 5% 13% 21% 19% 2	5288
	21st to end	Day	41% 4 11% 26% 16% 3	5812
February	1st to 10th	Day	43% 6% 16% 22% 11% 3	1890
	11th to 20th	Day	36% 6% 15% 24% 16% 4	2054
	21st to end	Day	30% 6% 11% 28% 19% 5%	1730
March	1st to 10th	Day	32% 4 8% 22% 26% 8%	4735
	11th to 20th	Day	30% 4 9% 24% 25% 7%	5090
	21st to end	Day	40% 7% 20% 24% 7% 2	5585
April	1st to 10th	Day	35% 6% 15% 26% 16% 2	2389
	11th to 20th	Day	38% 5% 14% 23% 16% 3	2636
	21st to end	Day	42% 7% 12% 24% 14% 1	2730
May	1st to 10th	Day	33% 6% 11% 26% 22% 3	7655
	11th to 20th	Day	32% 5% 10% 24% 22% 6%	7631
	21st to end	Day	43% 7% 11% 26% 13% 1	8405
June	1st to 10th	Day	26% 8% 18% 31% 15% 2	2730
	11th to 20th	Day	29% 7% 14% 29% 18% 3	2935
	21st to end	Day	27% 7% 14% 28% 19% 4	2940
July	1st to 10th	Day	30% 6% 11% 30% 21% 2	8181
	11th to 20th	Day	23% 6% 12% 30% 20% 9%	7843
	21st to end	Day	33% 7% 15% 23% 17% 4	8155
August	1st to 10th	Day	32% 6% 13% 24% 22% 3	6000
	11th to 20th	Day	38% 7% 18% 24% 12% 1	5987
	21st to end	Day	29% 6% 20% 23% 16% 6%	6413
September	1st to 10th	Day	32% 5% 11% 25% 21% 6%	2370
	11th to 20th	Day	30% 5% 12% 29% 22% 2	2310
	21st to end	Day	27% 4 9% 31% 25% 3	2288
October	1st to 10th	Day	21% 3 5% 20% 44% 7%	3524
	11th to 20th	Day	21% 3 11% 36% 21% 8%	3240
	21st to end	Day	29% 3 9% 30% 26% 3	3357
November	1st to 10th	Day	27% 5% 12% 30% 22% 3	1853
	11th to 20th	Day	29% 4 11% 27% 25% 4	1890
	21st to end	Day	35% 4 12% 26% 19% 4	1890
December	1st to 10th	Day	28% 3 11% 35% 20% 3	3030
	11th to 20th	Day	35% 4 18% 29% 13% 1	3479
	21st to end	Day	48% 5% 9% 26% 12% 1	4424
January	1st to 10th	Night	45% 4 11% 21% 16% 3	8188
	11th to 20th	Night	33% 4 14% 27% 21% 2	7680
	21st to end	Night	41% 5% 10% 21% 19% 5%	8402
February	1st to 10th	Night	40% 6% 13% 22% 15% 3	2730
	11th to 20th	Night	36% 6% 13% 26% 16% 3	2481
	21st to end	Night	30% 4 12% 22% 25% 7%	2076
March	1st to 10th	Night	29% 4 7% 25% 27% 7%	5353
	11th to 20th	Night	27% 4 7% 20% 30% 11%	5090
	21st to end	Night	39% 8% 20% 24% 8% 1	5588
April	1st to 10th	Night	34% 6% 13% 24% 20% 2	2226
	11th to 20th	Night	34% 7% 13% 26% 17% 3	1934
	21st to end	Night	34% 7% 14% 27% 18% 2	1890
May	1st to 10th	Night	35% 5% 9% 27% 22% 2	5293
	11th to 20th	Night	28% 6% 12% 25% 22% 6%	5266
	21st to end	Night	41% 7% 12% 24% 15% 1	5805
June	1st to 10th	Night	24% 10% 17% 29% 18% 2	1889
	11th to 20th	Night	26% 7% 14% 29% 18% 5%	1680
	21st to end	Night	23% 7% 17% 29% 21% 4	1680
July	1st to 10th	Night	30% 6% 14% 31% 17% 2	4700
	11th to 20th	Night	25% 6% 10% 29% 20% 9%	5008
	21st to end	Night	30% 6% 16% 25% 19% 4	5641
August	1st to 10th	Night	24% 6% 14% 29% 22% 4	4146
	11th to 20th	Night	33% 7% 24% 24% 11% 1	4145
	21st to end	Night	28% 6% 21% 27% 13% 6%	4718
September	1st to 10th	Night	23% 4 11% 28% 25% 9%	2248
	11th to 20th	Night	27% 6% 11% 29% 23% 4	2310
	21st to end	Night	27% 5% 9% 27% 27% 4	2288
October	1st to 10th	Night	20% 3 5% 19% 44% 8%	3621
	11th to 20th	Night	22% 3 10% 29% 26% 11%	3899
	21st to end	Night	27% 3 10% 28% 28% 4	4437
November	1st to 10th	Night	23% 4 11% 30% 26% 6%	2665
	11th to 20th	Night	26% 4 11% 29% 25% 5%	2730
	21st to end	Night	30% 4 12% 28% 23% 4	2730
December	1st to 10th	Night	22% 4 15% 37% 20% 2	4380
	11th to 20th	Night	29% 4 15% 34% 17% 2	4947
	21st to end	Night	45% 5% 10% 26% 12% 1	6768

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	16% 12% 40% 25% 6% 1	330
	11th to 20th	Day	16% 16% 38% 22% 8%	330
	21st to end	Day	13% 10% 44% 23% 8% 1	363
February	1st to 10th	Day	12% 16% 45% 22% 4 1	330
	11th to 20th	Day	13% 12% 41% 27% 6% 1	330
	21st to end	Day	10% 20% 47% 20% 3	273
March	1st to 10th	Day	15% 13% 45% 22% 5% 1	330
	11th to 20th	Day	24% 10% 37% 19% 10% 1	330
	21st to end	Day	22% 17% 40% 17% 4 1	363
April	1st to 10th	Day	17% 22% 40% 18% 3	409
	11th to 20th	Day	18% 18% 36% 24% 4	674
	21st to end	Day	24% 14% 33% 20% 8% 2	750
May	1st to 10th	Day	14% 13% 32% 30% 11% 1	753
	11th to 20th	Day	18% 11% 32% 25% 12% 2	775
	21st to end	Day	18% 8% 32% 27% 13% 2	844
June	1st to 10th	Day	5% 8% 28% 35% 19% 5%	780
	11th to 20th	Day	10% 7% 36% 30% 15% 1	780
	21st to end	Day	9% 8% 33% 33% 15% 2	780
July	1st to 10th	Day	9% 5% 19% 37% 25% 5%	771
	11th to 20th	Day	4 3 20% 42% 25% 6%	768
	21st to end	Day	8% 3 18% 40% 26% 5%	849
August	1st to 10th	Day	10% 2 19% 44% 22% 3	776
	11th to 20th	Day	6% 4 22% 42% 24% 2	765
	21st to end	Day	10% 1 23% 40% 20% 5%	783
September	1st to 10th	Day	14% 4 27% 36% 15% 4	420
	11th to 20th	Day	12% 7% 28% 34% 15% 5%	360
	21st to end	Day	17% 7% 27% 29% 16% 4	354
October	1st to 10th	Day	20% 7% 25% 30% 14% 4	330
	11th to 20th	Day	12% 13% 42% 22% 10% 1	330
	21st to end	Day	20% 15% 36% 20% 8% 1	363
November	1st to 10th	Day	12% 15% 39% 23% 8% 2	330
	11th to 20th	Day	11% 18% 42% 19% 8%	330
	21st to end	Day	19% 14% 35% 22% 9% 2	330
December	1st to 10th	Day	7% 11% 45% 28% 8% 1	330
	11th to 20th	Day	15% 12% 41% 25% 8%	330
	21st to end	Day	17% 12% 45% 23% 3	363
January	1st to 10th	Night	12% 11% 39% 32% 6% 1	1050
	11th to 20th	Night	11% 12% 40% 30% 6% 1	1050
	21st to end	Night	11% 10% 43% 29% 7%	1155
February	1st to 10th	Night	14% 11% 43% 28% 4	1050
	11th to 20th	Night	10% 13% 42% 31% 4	847
	21st to end	Night	11% 12% 46% 27% 4	692
March	1st to 10th	Night	12% 14% 42% 28% 3 1	777
	11th to 20th	Night	16% 11% 41% 26% 6%	630
	21st to end	Night	16% 13% 44% 23% 4	693
April	1st to 10th	Night	15% 15% 41% 25% 3	630
	11th to 20th	Night	16% 15% 43% 23% 4	623
	21st to end	Night	17% 14% 34% 29% 6% 1	630
May	1st to 10th	Night	18% 8% 36% 31% 7%	630
	11th to 20th	Night	16% 8% 35% 33% 7%	621
	21st to end	Night	16% 9% 31% 32% 11% 1	683
June	1st to 10th	Night	8% 5% 26% 45% 13% 2	630
	11th to 20th	Night	8% 6% 38% 37% 11%	630
	21st to end	Night	5% 7% 37% 39% 11%	630
July	1st to 10th	Night	7% 3 22% 45% 23%	615
	11th to 20th	Night	3 2 22% 52% 20% 1	612
	21st to end	Night	4 2 18% 53% 23%	690
August	1st to 10th	Night	6% 3 21% 51% 18% 2	627
	11th to 20th	Night	6% 4 23% 49% 17% 1	624
	21st to end	Night	8% 3 23% 44% 21% 2	693
September	1st to 10th	Night	10% 2 28% 44% 15% 1	630
	11th to 20th	Night	10% 4 34% 38% 13% 1	630
	21st to end	Night	8% 6% 35% 34% 15% 1	624
October	1st to 10th	Night	16% 7% 33% 31% 13%	618
	11th to 20th	Night	14% 10% 38% 31% 8%	800
	21st to end	Night	15% 13% 32% 31% 9%	990
November	1st to 10th	Night	8% 10% 37% 37% 7%	1025
	11th to 20th	Night	11% 11% 40% 31% 6%	1050
	21st to end	Night	12% 11% 35% 31% 11%	1050
December	1st to 10th	Night	10% 11% 42% 32% 5%	1050
	11th to 20th	Night	13% 11% 39% 30% 7%	1050
	21st to end	Night	15% 11% 39% 29% 5%	1155

Page generated at 2026-09-26 03:18:44. Version ac07

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