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 2025-05-26.

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%	118699
	Night	8% 6% 2 6% 4 4 4 3 5% 7% 52%	119299
Transparency	Day	33% 6% 13% 26% 19% 4	118456
	Night	31% 5% 12% 26% 21% 4	119132
Seeing	Day	13% 9% 32% 30% 14% 2	16453
	Night	11% 9% 36% 34% 9% 1	26455

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% 13% 4 10% 5% 5% 4 3 5% 5% 37%	3638
	11th to 20th	Day	4 10% 4 9% 5% 5% 4 3 5% 7% 45%	4058
	21st to end	Day	5% 7% 4 12% 4 4 4 3 4 5% 48%	4488
February	1st to 10th	Day	9% 11% 4 8% 5% 4 4 4 6% 6% 39%	1800
	11th to 20th	Day	6% 9% 3 7% 4 4 4 3 5% 8% 47%	1944
	21st to end	Day	8% 6% 2 6% 4 3 4 3 5% 6% 53%	1650
March	1st to 10th	Day	11% 8% 2 5% 2 3 2 2 3 4 57%	4632
	11th to 20th	Day	9% 7% 2 5% 3 3 3 2 4 7% 55%	4980
	21st to end	Day	13% 9% 3 6% 4 4 4 3 5% 8% 41%	5464
April	1st to 10th	Day	11% 7% 3 5% 4 3 5% 3 5% 6% 48%	2275
	11th to 20th	Day	13% 7% 2 6% 5% 4 3 3 6% 7% 44%	2506
	21st to end	Day	18% 7% 2 6% 4 3 4 4 5% 7% 41%	2600
May	1st to 10th	Day	13% 6% 2 5% 4 4 4 4 6% 7% 43%	4250
	11th to 20th	Day	13% 6% 3 5% 4 4 4 3 5% 6% 48%	4212
	21st to end	Day	14% 6% 2 6% 4 4 4 4 6% 7% 43%	4555
June	1st to 10th	Day	5% 4 2 5% 4 3 4 4 6% 8% 55%	2470
	11th to 20th	Day	8% 4 2 5% 4 4 4 4 6% 8% 51%	2655
	21st to end	Day	6% 3 1 5% 4 4 4 4 7% 9% 53%	2660
July	1st to 10th	Day	9% 6% 2 6% 4 4 4 3 5% 7% 50%	4430
	11th to 20th	Day	6% 4 2 5% 4 5% 4 4 6% 9% 51%	4253
	21st to end	Day	4 4 2 5% 4 4 4 4 7% 8% 55%	4466
August	1st to 10th	Day	8% 5% 2 7% 4 4 4 4 7% 9% 46%	4103
	11th to 20th	Day	12% 6% 2 6% 4 4 4 4 6% 7% 46%	4041
	21st to end	Day	5% 4 2 5% 4 3 3 3 5% 7% 58%	4413
September	1st to 10th	Day	11% 5% 2 5% 4 4 4 2 3 6% 55%	2144
	11th to 20th	Day	8% 4 2 5% 4 3 3 3 4 7% 57%	2090
	21st to end	Day	9% 4 1 4 3 3 3 3 4 7% 60%	2090
October	1st to 10th	Day	9% 3 1 3 2 2 2 2 3 4 70%	3416
	11th to 20th	Day	6% 4 1 3 2 2 3 3 4 7% 66%	3140
	21st to end	Day	9% 5% 2 5% 2 2 3 2 4 6% 58%	3253
November	1st to 10th	Day	9% 5% 1 4 2 4 4 3 6% 7% 56%	1763
	11th to 20th	Day	6% 7% 2 5% 3 3 2 3 5% 5% 57%	1800
	21st to end	Day	9% 8% 3 5% 4 3 3 3 4 7% 51%	1800
December	1st to 10th	Day	4 5% 2 6% 4 3 4 3 5% 6% 58%	2940
	11th to 20th	Day	6% 7% 3 8% 5% 4 4 3 5% 6% 50%	3391
	21st to end	Day	13% 10% 3 11% 5% 4 4 3 5% 5% 38%	4329
January	1st to 10th	Night	7% 11% 5% 12% 4 4 4 3 6% 7% 37%	6313
	11th to 20th	Night	4 7% 2 7% 5% 5% 5% 3 5% 7% 51%	5900
	21st to end	Night	6% 9% 4 11% 4 3 4 3 4 5% 47%	6490
February	1st to 10th	Night	8% 11% 4 6% 5% 5% 4 4 5% 6% 43%	2600
	11th to 20th	Night	6% 8% 3 8% 5% 4 4 4 6% 7% 46%	2360
	21st to end	Night	6% 7% 2 6% 4 4 3 3 4 6% 54%	1980
March	1st to 10th	Night	9% 5% 2 5% 3 4 3 3 5% 5% 57%	5236
	11th to 20th	Night	9% 5% 2 4 3 3 3 3 4 6% 59%	4980
	21st to end	Night	12% 7% 3 6% 4 5% 5% 4 6% 7% 41%	5467
April	1st to 10th	Night	10% 6% 2 5% 4 4 3 3 5% 6% 48%	2120
	11th to 20th	Night	12% 6% 2 4 5% 4 4 3 5% 9% 46%	1841
	21st to end	Night	13% 6% 3 6% 3 3 3 3 4 9% 48%	1800
May	1st to 10th	Night	20% 7% 2 4 3 3 3 4 5% 6% 44%	2940
	11th to 20th	Night	11% 6% 2 5% 4 4 4 3 6% 8% 47%	2913
	21st to end	Night	14% 6% 2 5% 3 4 4 3 6% 9% 41%	3148
June	1st to 10th	Night	5% 3 1 4 3 3 5% 4 7% 9% 55%	1709
	11th to 20th	Night	8% 4 2 4 3 3 4 4 7% 8% 54%	1520
	21st to end	Night	3 3 1 4 3 3 4 4 6% 10% 59%	1520
July	1st to 10th	Night	9% 4 2 5% 4 3 4 3 5% 7% 53%	2540
	11th to 20th	Night	5% 3 2 3 4 3 4 4 7% 10% 54%	2714
	21st to end	Night	3 3 1 3 3 3 3 3 6% 9% 63%	3097
August	1st to 10th	Night	5% 3 2 4 4 4 5% 4 6% 10% 53%	2836
	11th to 20th	Night	10% 5% 2 5% 3 3 4 4 6% 8% 50%	2798
	21st to end	Night	4 3 1 5% 3 4 4 4 6% 9% 57%	3252
September	1st to 10th	Night	9% 3 1 2 2 3 2 2 4 7% 64%	2034
	11th to 20th	Night	7% 4 2 4 3 4 4 3 5% 6% 59%	2090
	21st to end	Night	7% 3 2 4 3 3 3 2 5% 6% 61%	2090
October	1st to 10th	Night	8% 3 1 3 2 2 2 2 3 5% 70%	3510
	11th to 20th	Night	6% 3 1 3 3 3 3 2 4 6% 66%	3779
	21st to end	Night	8% 4 1 4 3 3 3 2 4 7% 60%	4299
November	1st to 10th	Night	6% 4 1 4 3 3 3 2 5% 7% 62%	2535
	11th to 20th	Night	7% 5% 2 3 4 3 3 3 5% 6% 58%	2600
	21st to end	Night	8% 6% 2 4 3 3 3 3 5% 7% 57%	2600
December	1st to 10th	Night	3 5% 1 3 4 2 3 3 5% 7% 64%	4250
	11th to 20th	Night	7% 4 2 5% 3 4 4 3 6% 8% 53%	4816
	21st to end	Night	13% 11% 3 9% 5% 4 4 3 4 6% 39%	6622

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	47% 5% 12% 22% 12% 1	3639
	11th to 20th	Day	39% 6% 12% 21% 19% 3	4058
	21st to end	Day	38% 5% 12% 26% 16% 3	4488
February	1st to 10th	Day	44% 6% 16% 21% 10% 3	1800
	11th to 20th	Day	36% 6% 16% 23% 16% 4	1954
	21st to end	Day	31% 6% 12% 27% 18% 6%	1650
March	1st to 10th	Day	32% 4 8% 22% 26% 8%	4632
	11th to 20th	Day	30% 4 9% 24% 26% 8%	4980
	21st to end	Day	40% 7% 21% 24% 7% 1	5464
April	1st to 10th	Day	35% 6% 15% 26% 16% 2	2275
	11th to 20th	Day	39% 6% 14% 24% 15% 3	2509
	21st to end	Day	42% 7% 12% 25% 14% 1	2600
May	1st to 10th	Day	35% 8% 14% 23% 15% 4	4250
	11th to 20th	Day	36% 7% 13% 28% 15% 1	4216
	21st to end	Day	37% 9% 13% 28% 12% 1	4555
June	1st to 10th	Day	25% 8% 18% 33% 15% 2	2470
	11th to 20th	Day	29% 8% 14% 29% 17% 3	2655
	21st to end	Day	25% 8% 15% 29% 18% 4	2660
July	1st to 10th	Day	34% 5% 10% 27% 22% 2	4361
	11th to 20th	Day	29% 7% 13% 28% 20% 3	4179
	21st to end	Day	23% 8% 14% 24% 24% 7%	4325
August	1st to 10th	Day	33% 7% 16% 24% 17% 4	4090
	11th to 20th	Day	38% 6% 15% 22% 17% 1	4080
	21st to end	Day	26% 6% 13% 24% 22% 8%	4412
September	1st to 10th	Day	31% 5% 11% 24% 22% 7%	2144
	11th to 20th	Day	27% 5% 12% 30% 23% 3	2090
	21st to end	Day	25% 4 10% 32% 26% 2	2090
October	1st to 10th	Day	20% 3 6% 20% 44% 7%	3416
	11th to 20th	Day	20% 3 11% 36% 21% 9%	3140
	21st to end	Day	29% 3 9% 30% 26% 3	3253
November	1st to 10th	Day	28% 5% 13% 30% 21% 4	1763
	11th to 20th	Day	29% 4 11% 26% 26% 4	1800
	21st to end	Day	34% 5% 12% 26% 19% 4	1800
December	1st to 10th	Day	28% 3 11% 35% 20% 3	2940
	11th to 20th	Day	35% 4 18% 29% 13% 1	3389
	21st to end	Day	48% 5% 9% 26% 11% 1	4329
January	1st to 10th	Night	47% 4 11% 22% 15% 1	6313
	11th to 20th	Night	34% 4 12% 26% 22% 2	5900
	21st to end	Night	39% 5% 9% 22% 19% 5%	6490
February	1st to 10th	Night	41% 7% 13% 22% 14% 4	2600
	11th to 20th	Night	36% 6% 13% 26% 16% 3	2360
	21st to end	Night	30% 4 13% 22% 24% 8%	1980
March	1st to 10th	Night	29% 4 7% 26% 27% 7%	5236
	11th to 20th	Night	27% 4 7% 20% 31% 11%	4980
	21st to end	Night	39% 8% 20% 24% 8% 1	5467
April	1st to 10th	Night	34% 6% 13% 24% 20% 2	2120
	11th to 20th	Night	35% 6% 14% 26% 17% 2	1841
	21st to end	Night	34% 7% 14% 26% 18% 2	1800
May	1st to 10th	Night	39% 7% 11% 25% 15% 3	2940
	11th to 20th	Night	33% 9% 14% 25% 18% 1	2914
	21st to end	Night	36% 10% 17% 22% 13% 1	3149
June	1st to 10th	Night	22% 10% 18% 30% 18% 2	1709
	11th to 20th	Night	27% 8% 15% 28% 18% 5%	1520
	21st to end	Night	20% 7% 17% 31% 21% 4	1520
July	1st to 10th	Night	29% 6% 13% 28% 19% 3	2500
	11th to 20th	Night	23% 7% 14% 33% 18% 4	2665
	21st to end	Night	17% 6% 17% 27% 25% 8%	2999
August	1st to 10th	Night	24% 7% 17% 26% 19% 5%	2826
	11th to 20th	Night	32% 6% 19% 26% 16% 2	2825
	21st to end	Night	24% 5% 16% 28% 19% 9%	3252
September	1st to 10th	Night	22% 4 11% 27% 27% 10%	2034
	11th to 20th	Night	25% 6% 10% 30% 25% 5%	2090
	21st to end	Night	24% 5% 9% 28% 29% 4	2090
October	1st to 10th	Night	19% 3 5% 18% 45% 9%	3510
	11th to 20th	Night	21% 3 10% 29% 26% 11%	3779
	21st to end	Night	26% 3 10% 28% 28% 4	4299
November	1st to 10th	Night	23% 5% 12% 29% 25% 7%	2535
	11th to 20th	Night	26% 4 10% 29% 25% 5%	2600
	21st to end	Night	28% 4 12% 28% 23% 4	2600
December	1st to 10th	Night	21% 4 15% 37% 20% 2	4250
	11th to 20th	Night	29% 4 15% 34% 17% 2	4817
	21st to end	Night	45% 5% 10% 26% 12% 1	6622

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% 40% 25% 7% 1	300
	11th to 20th	Day	15% 15% 37% 24% 9%	300
	21st to end	Day	13% 10% 44% 24% 8% 1	330
February	1st to 10th	Day	14% 15% 44% 22% 4 1	300
	11th to 20th	Day	13% 12% 41% 27% 6% 1	300
	21st to end	Day	10% 20% 46% 20% 3	249
March	1st to 10th	Day	14% 13% 43% 23% 5% 1	300
	11th to 20th	Day	23% 9% 38% 20% 10% 1	300
	21st to end	Day	22% 15% 40% 17% 5% 1	330
April	1st to 10th	Day	17% 21% 40% 19% 3	375
	11th to 20th	Day	18% 17% 36% 24% 4	627
	21st to end	Day	23% 14% 34% 19% 8% 2	700
May	1st to 10th	Day	14% 12% 31% 30% 11% 1	703
	11th to 20th	Day	18% 10% 33% 25% 12% 2	725
	21st to end	Day	18% 8% 32% 27% 13% 2	760
June	1st to 10th	Day	4 7% 26% 36% 21% 5%	680
	11th to 20th	Day	10% 6% 36% 30% 15% 2	680
	21st to end	Day	7% 7% 33% 34% 17% 2	680
July	1st to 10th	Day	9% 4 18% 38% 26% 6%	671
	11th to 20th	Day	4 3 20% 44% 24% 5%	668
	21st to end	Day	7% 2 18% 40% 27% 6%	739
August	1st to 10th	Day	9% 2 18% 44% 24% 4	676
	11th to 20th	Day	7% 3 23% 41% 25% 2	665
	21st to end	Day	10% 1 22% 41% 21% 5%	681
September	1st to 10th	Day	14% 4 25% 37% 16% 5%	354
	11th to 20th	Day	7% 6% 28% 37% 16% 5%	300
	21st to end	Day	13% 8% 29% 29% 17% 4	300
October	1st to 10th	Day	21% 6% 24% 30% 15% 4	300
	11th to 20th	Day	10% 13% 42% 23% 11% 1	300
	21st to end	Day	18% 14% 37% 22% 8% 1	330
November	1st to 10th	Day	13% 15% 37% 25% 8% 3	300
	11th to 20th	Day	11% 18% 42% 20% 8%	300
	21st to end	Day	18% 15% 34% 22% 9% 2	300
December	1st to 10th	Day	7% 9% 45% 30% 8% 1	300
	11th to 20th	Day	15% 9% 41% 27% 7%	300
	21st to end	Day	18% 13% 44% 22% 3	330
January	1st to 10th	Night	12% 11% 39% 32% 6% 1	1000
	11th to 20th	Night	10% 12% 40% 31% 7% 1	1000
	21st to end	Night	11% 9% 43% 30% 7%	1100
February	1st to 10th	Night	14% 11% 42% 27% 5%	1000
	11th to 20th	Night	10% 13% 42% 31% 4	806
	21st to end	Night	11% 12% 45% 27% 5%	660
March	1st to 10th	Night	12% 13% 42% 29% 3 1	740
	11th to 20th	Night	15% 11% 41% 27% 6% 1	600
	21st to end	Night	17% 13% 42% 23% 5%	660
April	1st to 10th	Night	15% 15% 42% 26% 3	600
	11th to 20th	Night	16% 13% 43% 23% 4	593
	21st to end	Night	17% 13% 33% 30% 6% 1	600
May	1st to 10th	Night	18% 8% 35% 32% 7%	600
	11th to 20th	Night	16% 8% 35% 34% 7% 1	591
	21st to end	Night	17% 9% 31% 31% 11% 1	634
June	1st to 10th	Night	7% 5% 26% 47% 14% 2	570
	11th to 20th	Night	8% 6% 38% 36% 12%	570
	21st to end	Night	3 6% 37% 42% 12%	570
July	1st to 10th	Night	7% 3 21% 44% 25% 1	555
	11th to 20th	Night	3 1 22% 53% 20% 1	552
	21st to end	Night	3 2 17% 53% 25%	624
August	1st to 10th	Night	6% 2 18% 52% 19% 2	567
	11th to 20th	Night	7% 3 23% 50% 17% 1	564
	21st to end	Night	7% 3 23% 44% 21% 2	627
September	1st to 10th	Night	10% 2 26% 44% 16% 1	570
	11th to 20th	Night	9% 3 34% 38% 15% 1	570
	21st to end	Night	8% 5% 37% 35% 15% 1	570
October	1st to 10th	Night	16% 7% 33% 31% 13%	587
	11th to 20th	Night	13% 9% 37% 32% 8%	760
	21st to end	Night	14% 13% 32% 31% 10%	940
November	1st to 10th	Night	8% 10% 36% 38% 7%	975
	11th to 20th	Night	11% 12% 40% 31% 7%	1000
	21st to end	Night	11% 11% 35% 31% 11%	1000
December	1st to 10th	Night	9% 11% 42% 32% 5%	1000
	11th to 20th	Night	13% 11% 39% 30% 7%	1000
	21st to end	Night	15% 11% 38% 30% 5%	1100

Page generated at 2025-05-23 08:21:03. Version ac07

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