Hyampom
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hyampom clear sky chart from 2005-11-06 to 2024-11-30.

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	8% 7% 2 5% 3 3 3 3 4 6% 55%	105442
	Night	9% 8% 3 7% 4 4 4 3 4 5% 48%	102875
Transparency	Day	31% 5% 9% 20% 21% 15%	105197
	Night	36% 6% 10% 17% 19% 12%	102709
Seeing	Day	16% 13% 26% 25% 15% 5%	15236
	Night	14% 8% 18% 30% 25% 5%	24368

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	16% 20% 4 10% 5% 5% 5% 3 5% 5% 22%	2585
	11th to 20th	Day	22% 17% 3 8% 5% 5% 4 2 4 4 25%	2860
	21st to end	Day	24% 12% 4 8% 4 4 4 3 4 6% 26%	3146
February	1st to 10th	Day	16% 10% 3 7% 4 5% 4 4 5% 5% 37%	1710
	11th to 20th	Day	11% 12% 3 8% 5% 4 4 4 5% 8% 36%	1665
	21st to end	Day	14% 16% 4 8% 4 3 4 3 5% 8% 32%	1534
March	1st to 10th	Day	16% 24% 6% 10% 5% 3 3 3 3 4 24%	3442
	11th to 20th	Day	12% 10% 3 6% 4 3 3 2 3 6% 49%	3490
	21st to end	Day	16% 16% 4 10% 6% 6% 4 3 5% 6% 24%	3825
April	1st to 10th	Day	13% 13% 3 8% 5% 5% 4 3 6% 8% 32%	2268
	11th to 20th	Day	13% 12% 3 6% 4 3 4 4 5% 8% 39%	2249
	21st to end	Day	7% 9% 3 5% 5% 3 4 4 6% 8% 46%	2371
May	1st to 10th	Day	6% 8% 3 6% 4 3 4 3 4 6% 55%	4110
	11th to 20th	Day	4 3 1 4 2 2 2 2 3 5% 70%	4239
	21st to end	Day	5% 4 1 3 3 3 3 3 5% 7% 63%	4813
June	1st to 10th	Day	7% 5% 2 5% 4 4 4 4 5% 7% 52%	2660
	11th to 20th	Day	4 3 1 4 3 3 3 3 4 7% 65%	2660
	21st to end	Day	3 2 1 2 2 2 3 2 3 4 76%	2660
July	1st to 10th	Day	1 1 1 1 1 1 1 2 3 88%	4420
	11th to 20th	Day	2 2 1 2 1 1 2 2 3 3 82%	4269
	21st to end	Day	1 1 1 1 1 1 3 4 85%	4455
August	1st to 10th	Day	1 1 1 2 1 1 2 2 4 6% 79%	4091
	11th to 20th	Day	1 2 2 3 3 2 4 4 78%	4026
	21st to end	Day	2 2 1 2 2 1 2 2 4 5% 78%	4211
September	1st to 10th	Day	1 1 1 2 1 1 2 2 3 4 81%	2280
	11th to 20th	Day	3 2 1 5% 3 4 4 4 5% 7% 64%	2219
	21st to end	Day	4 2 1 4 2 3 2 2 4 6% 69%	2032
October	1st to 10th	Day	4 2 1 3 2 3 3 2 4 5% 72%	3180
	11th to 20th	Day	6% 3 1 4 3 4 5% 4 5% 8% 56%	3161
	21st to end	Day	8% 5% 2 7% 5% 7% 5% 4 6% 7% 44%	3448
November	1st to 10th	Day	13% 8% 2 7% 5% 5% 4 3 6% 8% 38%	1906
	11th to 20th	Day	14% 8% 2 8% 6% 5% 5% 4 8% 9% 31%	1620
	21st to end	Day	13% 9% 3 7% 5% 5% 4 3 5% 7% 39%	1595
December	1st to 10th	Day	13% 8% 3 8% 5% 5% 5% 3 6% 6% 37%	1520
	11th to 20th	Day	25% 12% 4 9% 6% 5% 4 3 4 5% 22%	1928
	21st to end	Day	19% 13% 4 9% 6% 5% 5% 4 5% 5% 22%	2794
January	1st to 10th	Night	15% 17% 5% 10% 6% 5% 4 4 6% 6% 23%	4344
	11th to 20th	Night	18% 16% 5% 12% 7% 5% 4 3 4 5% 22%	4110
	21st to end	Night	27% 15% 4 8% 5% 4 4 2 4 5% 23%	4521
February	1st to 10th	Night	13% 12% 3 8% 5% 4 5% 3 5% 7% 34%	2470
	11th to 20th	Night	11% 13% 3 10% 5% 5% 4 3 6% 6% 33%	2402
	21st to end	Night	11% 11% 4 8% 5% 6% 5% 4 5% 7% 34%	1918
March	1st to 10th	Night	13% 20% 7% 11% 5% 4 5% 3 4 5% 22%	3432
	11th to 20th	Night	11% 10% 2 7% 5% 3 3 2 4 6% 47%	3490
	21st to end	Night	11% 19% 6% 11% 7% 5% 5% 4 5% 4 23%	3828
April	1st to 10th	Night	11% 11% 4 9% 5% 5% 5% 3 7% 8% 32%	1910
	11th to 20th	Night	8% 10% 4 9% 6% 4 4 4 5% 7% 38%	1879
	21st to end	Night	5% 9% 2 8% 5% 3 4 4 6% 8% 45%	1805
May	1st to 10th	Night	7% 8% 3 5% 3 3 5% 2 4 5% 55%	2860
	11th to 20th	Night	2 2 1 4 3 3 3 3 3 5% 70%	2655
	21st to end	Night	3 4 1 3 2 3 3 3 4 7% 68%	2762
June	1st to 10th	Night	6% 5% 3 6% 4 4 4 4 7% 8% 50%	1520
	11th to 20th	Night	3 2 1 2 3 2 2 2 4 7% 70%	1520
	21st to end	Night	3 2 1 2 1 2 1 2 3 5% 78%	1520
July	1st to 10th	Night	1 1 1 1 1 1 1 2 2 89%	2540
	11th to 20th	Night	1 1 1 2 1 2 2 2 3 3 82%	2691
	21st to end	Night	1 2 1 1 1 2 3 3 86%	3109
August	1st to 10th	Night	1 2 2 2 2 3 4 4 80%	2848
	11th to 20th	Night	1 3 2 2 3 3 4 3 78%	2812
	21st to end	Night	2 1 1 3 2 2 3 2 2 3 78%	3464
September	1st to 10th	Night	1 2 1 3 1 1 2 2 3 4 81%	1900
	11th to 20th	Night	2 3 2 5% 3 3 3 3 4 7% 65%	1957
	21st to end	Night	3 3 1 6% 3 3 3 3 4 5% 66%	2147
October	1st to 10th	Night	3 1 1 5% 3 2 3 3 4 5% 69%	3800
	11th to 20th	Night	6% 5% 2 8% 4 4 4 3 5% 6% 51%	3777
	21st to end	Night	7% 5% 3 9% 6% 5% 6% 4 6% 6% 43%	4121
November	1st to 10th	Night	11% 8% 3 8% 6% 6% 5% 5% 5% 6% 37%	2390
	11th to 20th	Night	14% 9% 3 8% 6% 6% 6% 5% 6% 7% 30%	2775
	21st to end	Night	13% 8% 3 6% 5% 4 4 3 6% 7% 41%	2800
December	1st to 10th	Night	16% 9% 4 7% 5% 4 4 4 5% 7% 36%	2660
	11th to 20th	Night	25% 13% 3 8% 5% 4 4 4 5% 6% 24%	3276
	21st to end	Night	18% 13% 4 9% 6% 5% 5% 4 5% 5% 25%	4862

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	60% 9% 9% 14% 5% 3	2585
	11th to 20th	Day	61% 8% 7% 9% 8% 7%	2860
	21st to end	Day	58% 7% 10% 10% 10% 4	3146
February	1st to 10th	Day	47% 6% 9% 17% 13% 6%	1710
	11th to 20th	Day	46% 6% 10% 19% 16% 3	1674
	21st to end	Day	50% 8% 11% 15% 12% 3	1534
March	1st to 10th	Day	65% 6% 6% 13% 10% 1	3442
	11th to 20th	Day	38% 6% 11% 19% 23% 3	3490
	21st to end	Day	59% 8% 11% 15% 5% 1	3825
April	1st to 10th	Day	50% 8% 14% 16% 10% 2	2268
	11th to 20th	Day	43% 8% 12% 20% 12% 4	2252
	21st to end	Day	34% 8% 16% 24% 15% 2	2371
May	1st to 10th	Day	30% 7% 13% 24% 19% 6%	4110
	11th to 20th	Day	19% 4 7% 20% 40% 10%	4242
	21st to end	Day	20% 5% 17% 44% 13% 1	4814
June	1st to 10th	Day	30% 7% 13% 29% 18% 3	2660
	11th to 20th	Day	19% 5% 12% 27% 29% 8%	2660
	21st to end	Day	13% 3 7% 23% 35% 19%	2660
July	1st to 10th	Day	5% 1 3 12% 20% 57%	4351
	11th to 20th	Day	9% 1 3 12% 26% 48%	4194
	21st to end	Day	6% 1 4 17% 34% 38%	4315
August	1st to 10th	Day	9% 2 5% 17% 34% 35%	4076
	11th to 20th	Day	10% 2 7% 26% 35% 20%	4065
	21st to end	Day	10% 2 7% 24% 39% 17%	4210
September	1st to 10th	Day	8% 2 6% 14% 33% 37%	2280
	11th to 20th	Day	20% 4 8% 23% 34% 11%	2219
	21st to end	Day	16% 4 9% 22% 29% 21%	2032
October	1st to 10th	Day	16% 3 6% 20% 19% 37%	3180
	11th to 20th	Day	26% 4 11% 31% 19% 8%	3161
	21st to end	Day	36% 7% 9% 20% 19% 10%	3448
November	1st to 10th	Day	43% 7% 10% 18% 14% 8%	1906
	11th to 20th	Day	47% 7% 12% 14% 11% 8%	1620
	21st to end	Day	44% 6% 9% 14% 15% 12%	1595
December	1st to 10th	Day	47% 5% 8% 13% 18% 9%	1520
	11th to 20th	Day	64% 6% 7% 10% 11% 3	1928
	21st to end	Day	60% 9% 7% 11% 10% 3	2794
January	1st to 10th	Night	57% 11% 11% 11% 6% 3	4344
	11th to 20th	Night	62% 8% 7% 8% 7% 7%	4110
	21st to end	Night	64% 6% 6% 10% 9% 5%	4521
February	1st to 10th	Night	48% 6% 9% 18% 14% 6%	2470
	11th to 20th	Night	50% 7% 9% 16% 14% 4	2404
	21st to end	Night	47% 9% 13% 18% 10% 3	1918
March	1st to 10th	Night	62% 8% 8% 13% 8% 1	3432
	11th to 20th	Night	37% 7% 11% 23% 16% 6%	3490
	21st to end	Night	57% 12% 13% 12% 5% 1	3828
April	1st to 10th	Night	48% 9% 16% 15% 9% 3	1910
	11th to 20th	Night	43% 8% 16% 18% 11% 4	1879
	21st to end	Night	34% 9% 18% 26% 12% 2	1805
May	1st to 10th	Night	27% 7% 15% 22% 20% 8%	2860
	11th to 20th	Night	17% 5% 9% 18% 41% 10%	2655
	21st to end	Night	17% 6% 19% 44% 14%	2762
June	1st to 10th	Night	30% 7% 14% 30% 18% 2	1520
	11th to 20th	Night	13% 5% 13% 34% 27% 8%	1520
	21st to end	Night	12% 2 7% 26% 35% 18%	1520
July	1st to 10th	Night	5% 1 3 13% 22% 55%	2500
	11th to 20th	Night	8% 1 4 11% 25% 51%	2643
	21st to end	Night	5% 1 5% 11% 41% 37%	3011
August	1st to 10th	Night	9% 2 4 18% 32% 35%	2839
	11th to 20th	Night	9% 2 10% 19% 37% 22%	2839
	21st to end	Night	11% 2 6% 25% 39% 16%	3464
September	1st to 10th	Night	9% 2 6% 15% 33% 35%	1900
	11th to 20th	Night	18% 4 10% 27% 31% 11%	1957
	21st to end	Night	20% 5% 9% 20% 23% 23%	2147
October	1st to 10th	Night	18% 3 8% 13% 24% 35%	3800
	11th to 20th	Night	31% 5% 10% 28% 18% 8%	3777
	21st to end	Night	37% 6% 10% 17% 20% 10%	4121
November	1st to 10th	Night	45% 8% 12% 13% 15% 8%	2390
	11th to 20th	Night	49% 9% 12% 14% 10% 6%	2775
	21st to end	Night	42% 7% 9% 14% 17% 11%	2800
December	1st to 10th	Night	47% 6% 9% 12% 18% 8%	2660
	11th to 20th	Night	60% 6% 7% 11% 13% 2	3276
	21st to end	Night	57% 9% 10% 13% 8% 3	4862

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	41% 15% 22% 15% 6% 1	213
	11th to 20th	Day	31% 13% 26% 15% 11% 4	370
	21st to end	Day	25% 16% 22% 19% 14% 3	407
February	1st to 10th	Day	25% 16% 25% 19% 13% 1	370
	11th to 20th	Day	30% 18% 22% 19% 9% 2	365
	21st to end	Day	28% 20% 24% 18% 9% 1	361
March	1st to 10th	Day	33% 22% 25% 14% 4 2	460
	11th to 20th	Day	27% 18% 25% 18% 9% 2	460
	21st to end	Day	31% 22% 25% 16% 6%	506
April	1st to 10th	Day	26% 19% 27% 19% 8% 1	460
	11th to 20th	Day	28% 16% 25% 20% 9% 2	452
	21st to end	Day	17% 22% 30% 18% 11% 3	460
May	1st to 10th	Day	18% 19% 30% 20% 10% 3	463
	11th to 20th	Day	17% 19% 26% 23% 10% 5%	488
	21st to end	Day	15% 12% 29% 24% 15% 5%	529
June	1st to 10th	Day	12% 16% 26% 29% 12% 5%	490
	11th to 20th	Day	12% 17% 32% 23% 11% 5%	490
	21st to end	Day	2 10% 33% 28% 18% 8%	490
July	1st to 10th	Day	3 6% 29% 35% 18% 9%	486
	11th to 20th	Day	1 5% 28% 35% 24% 8%	484
	21st to end	Day	1 3 24% 37% 25% 11%	531
August	1st to 10th	Day	1 3 29% 35% 22% 9%	487
	11th to 20th	Day	2 6% 26% 33% 21% 12%	477
	21st to end	Day	3 4 24% 34% 27% 8%	539
September	1st to 10th	Day	2 9% 23% 39% 20% 7%	490
	11th to 20th	Day	7% 9% 26% 33% 21% 4	490
	21st to end	Day	7% 9% 26% 31% 22% 5%	490
October	1st to 10th	Day	9% 10% 25% 27% 21% 9%	490
	11th to 20th	Day	13% 9% 19% 26% 26% 7%	490
	21st to end	Day	16% 12% 21% 28% 18% 6%	539
November	1st to 10th	Day	19% 12% 25% 23% 13% 7%	442
	11th to 20th	Day	18% 13% 20% 25% 17% 8%	210
	21st to end	Day	21% 11% 21% 22% 20% 6%	199
December	1st to 10th	Day	24% 13% 22% 19% 12% 9%	180
	11th to 20th	Day	28% 17% 16% 22% 11% 6%	180
	21st to end	Day	27% 14% 22% 22% 15% 1	198
January	1st to 10th	Night	26% 8% 23% 26% 13% 4	760
	11th to 20th	Night	23% 10% 21% 27% 14% 5%	760
	21st to end	Night	22% 10% 21% 25% 17% 5%	836
February	1st to 10th	Night	21% 11% 21% 32% 13% 2	760
	11th to 20th	Night	21% 9% 22% 27% 17% 3	744
	21st to end	Night	20% 13% 25% 29% 13% 1	628
March	1st to 10th	Night	25% 17% 22% 22% 12% 3	760
	11th to 20th	Night	24% 10% 19% 28% 18% 2	760
	21st to end	Night	24% 14% 25% 23% 12% 2	836
April	1st to 10th	Night	17% 13% 25% 26% 16% 2	760
	11th to 20th	Night	17% 12% 23% 28% 16% 4	751
	21st to end	Night	13% 10% 23% 31% 20% 3	665
May	1st to 10th	Night	10% 9% 24% 32% 22% 4	570
	11th to 20th	Night	7% 7% 20% 29% 32% 4	461
	21st to end	Night	9% 7% 23% 31% 26% 3	411
June	1st to 10th	Night	7% 7% 20% 34% 30% 3	380
	11th to 20th	Night	4 5% 23% 41% 25% 1	380
	21st to end	Night	4 2 12% 40% 40% 3	380
July	1st to 10th	Night	2 1 10% 41% 42% 4	370
	11th to 20th	Night	2 7% 36% 48% 6%	454
	21st to end	Night	1 4 27% 57% 11%	624
August	1st to 10th	Night	1 5% 35% 49% 10%	567
	11th to 20th	Night	1 8% 37% 45% 9%	564
	21st to end	Night	1 1 10% 38% 43% 7%	815
September	1st to 10th	Night	2 2 14% 37% 38% 8%	760
	11th to 20th	Night	4 4 14% 36% 33% 9%	760
	21st to end	Night	5% 5% 15% 30% 36% 9%	760
October	1st to 10th	Night	7% 4 18% 31% 35% 5%	760
	11th to 20th	Night	11% 4 16% 29% 32% 8%	760
	21st to end	Night	14% 5% 14% 34% 24% 9%	836
November	1st to 10th	Night	15% 8% 20% 31% 21% 6%	780
	11th to 20th	Night	18% 9% 21% 31% 18% 3	800
	21st to end	Night	18% 10% 19% 31% 20% 4	800
December	1st to 10th	Night	22% 8% 19% 28% 18% 4	760
	11th to 20th	Night	28% 10% 17% 27% 14% 3	760
	21st to end	Night	29% 12% 20% 26% 11% 3	836

Page generated at 2024-11-27 14:30:51. Version ac07

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