Burley/Heyburn
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burley/Heyburn clear sky chart from 2005-11-06 to 2024-11-04.

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	5% 6% 2 5% 4 4 4 4 5% 7% 54%	104713
	Night	6% 7% 2 6% 4 4 4 4 6% 7% 50%	102991
Transparency	Day	31% 3 10% 21% 21% 14%	104463
	Night	34% 4 11% 21% 18% 12%	102831
Seeing	Day	9% 11% 24% 27% 21% 8%	14488
	Night	9% 8% 21% 37% 22% 3	24369

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	10% 16% 5% 11% 7% 5% 5% 4 6% 6% 24%	2539
	11th to 20th	Day	9% 14% 6% 11% 6% 5% 4 4 5% 7% 30%	2540
	21st to end	Day	10% 14% 4 9% 5% 5% 4 4 6% 8% 31%	3027
February	1st to 10th	Day	7% 13% 4 11% 5% 4 5% 4 6% 7% 34%	1710
	11th to 20th	Day	8% 13% 3 8% 6% 5% 5% 3 6% 7% 37%	1797
	21st to end	Day	6% 12% 4 10% 6% 5% 4 3 6% 8% 35%	1570
March	1st to 10th	Day	8% 13% 5% 10% 5% 5% 4 4 5% 8% 33%	3189
	11th to 20th	Day	5% 9% 2 6% 4 3 4 4 5% 6% 52%	3490
	21st to end	Day	8% 11% 4 9% 6% 6% 7% 4 7% 8% 30%	3825
April	1st to 10th	Day	8% 10% 3 6% 5% 4 5% 4 7% 7% 41%	2217
	11th to 20th	Day	6% 9% 3 6% 5% 5% 4 4 6% 7% 45%	2388
	21st to end	Day	7% 6% 2 6% 5% 5% 4 3 6% 8% 48%	2470
May	1st to 10th	Day	7% 8% 3 7% 5% 5% 5% 4 6% 8% 44%	4110
	11th to 20th	Day	4 3 1 3 3 2 3 4 5% 7% 63%	4071
	21st to end	Day	6% 5% 1 5% 4 4 5% 4 6% 8% 51%	4528
June	1st to 10th	Day	5% 4 1 4 4 4 5% 4 7% 9% 52%	2660
	11th to 20th	Day	5% 4 2 4 3 3 4 3 4 7% 62%	2660
	21st to end	Day	2 1 1 2 2 2 3 3 5% 5% 74%	2660
July	1st to 10th	Day	1 1 2 2 2 2 2 4 4 80%	4420
	11th to 20th	Day	2 2 1 3 2 3 4 4 5% 6% 68%	4420
	21st to end	Day	2 3 1 3 3 3 4 3 5% 6% 67%	4578
August	1st to 10th	Day	2 3 1 3 3 4 4 4 6% 8% 62%	4092
	11th to 20th	Day	2 1 1 2 2 2 3 2 4 6% 75%	4028
	21st to end	Day	1 2 1 3 2 2 3 3 4 5% 74%	4433
September	1st to 10th	Day	3 2 1 2 2 2 3 3 5% 7% 71%	2180
	11th to 20th	Day	3 3 2 3 2 2 3 3 5% 6% 67%	2090
	21st to end	Day	5% 4 1 4 3 3 3 2 4 4 67%	2090
October	1st to 10th	Day	5% 3 1 4 3 3 3 3 4 5% 67%	3458
	11th to 20th	Day	5% 5% 2 4 3 3 3 2 4 5% 65%	3150
	21st to end	Day	4 5% 2 5% 3 4 4 4 6% 8% 54%	3141
November	1st to 10th	Day	7% 9% 2 6% 5% 4 5% 4 5% 9% 44%	1701
	11th to 20th	Day	9% 6% 2 7% 5% 4 5% 5% 6% 8% 43%	1710
	21st to end	Day	6% 11% 3 6% 5% 5% 4 4 6% 9% 42%	1669
December	1st to 10th	Day	8% 11% 4 7% 6% 5% 4 4 5% 6% 39%	1520
	11th to 20th	Day	10% 11% 4 8% 4 6% 6% 5% 8% 10% 30%	1788
	21st to end	Day	8% 13% 4 8% 4 4 4 4 7% 8% 36%	2794
January	1st to 10th	Night	9% 14% 5% 10% 5% 5% 5% 4 7% 8% 29%	4406
	11th to 20th	Night	10% 14% 5% 11% 6% 5% 6% 4 5% 7% 26%	4420
	21st to end	Night	10% 14% 4 10% 5% 5% 5% 4 6% 7% 31%	4633
February	1st to 10th	Night	9% 10% 4 8% 6% 5% 5% 5% 7% 8% 33%	2470
	11th to 20th	Night	7% 10% 3 8% 5% 4 5% 3 5% 8% 43%	2267
	21st to end	Night	5% 9% 4 8% 5% 4 5% 5% 8% 10% 37%	1884
March	1st to 10th	Night	7% 12% 3 8% 5% 5% 5% 4 6% 8% 38%	3685
	11th to 20th	Night	4 8% 2 5% 4 4 3 4 6% 7% 52%	3490
	21st to end	Night	7% 9% 3 8% 5% 5% 6% 4 7% 9% 36%	3828
April	1st to 10th	Night	6% 9% 2 7% 6% 5% 4 4 6% 7% 44%	1960
	11th to 20th	Night	7% 8% 2 6% 5% 4 5% 4 5% 6% 49%	1739
	21st to end	Night	7% 5% 2 6% 4 3 4 4 6% 8% 52%	1710
May	1st to 10th	Night	10% 8% 2 6% 4 4 4 3 5% 7% 47%	2860
	11th to 20th	Night	3 3 1 5% 3 3 4 4 6% 6% 62%	2834
	21st to end	Night	6% 6% 1 5% 4 4 4 4 6% 7% 53%	3053
June	1st to 10th	Night	4 3 1 5% 3 4 5% 5% 7% 10% 53%	1520
	11th to 20th	Night	4 4 1 5% 2 3 3 3 5% 8% 62%	1520
	21st to end	Night	3 2 1 2 3 2 4 2 4 6% 72%	1520
July	1st to 10th	Night	1 1 1 2 1 2 3 2 4 6% 76%	2540
	11th to 20th	Night	1 2 1 3 3 2 3 2 6% 6% 72%	2540
	21st to end	Night	1 2 1 4 3 4 4 4 5% 8% 64%	2977
August	1st to 10th	Night	2 2 1 4 3 3 4 4 5% 8% 64%	2847
	11th to 20th	Night	2 2 1 3 2 3 3 3 5% 7% 68%	2811
	21st to end	Night	2 2 1 3 2 2 2 3 3 4 76%	3233
September	1st to 10th	Night	2 2 1 2 2 2 3 2 4 7% 73%	1998
	11th to 20th	Night	4 3 1 5% 2 3 3 3 4 7% 65%	2090
	21st to end	Night	5% 3 1 3 3 3 3 2 3 5% 69%	2090
October	1st to 10th	Night	4 3 1 3 2 2 3 2 3 5% 71%	3521
	11th to 20th	Night	6% 6% 2 5% 3 3 4 3 4 6% 58%	3778
	21st to end	Night	5% 6% 2 5% 3 4 5% 4 7% 9% 51%	4413
November	1st to 10th	Night	9% 8% 2 6% 4 4 4 4 6% 7% 46%	2450
	11th to 20th	Night	8% 6% 2 6% 5% 5% 4 4 7% 9% 44%	2470
	21st to end	Night	6% 8% 2 6% 4 5% 5% 4 7% 9% 45%	2486
December	1st to 10th	Night	9% 11% 4 7% 5% 4 5% 4 7% 8% 36%	2660
	11th to 20th	Night	10% 11% 4 10% 6% 5% 5% 5% 7% 9% 29%	3426
	21st to end	Night	9% 10% 5% 10% 5% 5% 4 4 6% 8% 34%	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	61% 3 16% 17% 2 1	2539
	11th to 20th	Day	56% 5% 19% 16% 4 1	2540
	21st to end	Day	51% 5% 22% 17% 5% 1	3027
February	1st to 10th	Day	50% 5% 19% 20% 5% 1	1710
	11th to 20th	Day	47% 4 16% 22% 9% 1	1807
	21st to end	Day	48% 5% 13% 22% 9% 2	1570
March	1st to 10th	Day	48% 6% 10% 27% 8% 1	3189
	11th to 20th	Day	34% 4 11% 34% 16% 1	3490
	21st to end	Day	52% 4 20% 17% 6% 1	3825
April	1st to 10th	Day	42% 4 13% 22% 14% 4	2217
	11th to 20th	Day	39% 4 10% 27% 17% 4	2391
	21st to end	Day	35% 3 13% 27% 21% 2	2470
May	1st to 10th	Day	37% 5% 6% 29% 20% 3	4110
	11th to 20th	Day	20% 3 8% 31% 31% 7%	4074
	21st to end	Day	30% 4 13% 28% 22% 3	4528
June	1st to 10th	Day	28% 4 14% 31% 20% 3	2660
	11th to 20th	Day	24% 3 8% 25% 30% 10%	2660
	21st to end	Day	12% 3 5% 22% 36% 22%	2660
July	1st to 10th	Day	9% 2 2 11% 21% 55%	4351
	11th to 20th	Day	15% 3 3 8% 24% 47%	4345
	21st to end	Day	18% 2 3 10% 27% 40%	4433
August	1st to 10th	Day	19% 3 4 15% 25% 34%	4078
	11th to 20th	Day	12% 3 3 14% 39% 30%	4067
	21st to end	Day	14% 2 3 14% 35% 32%	4432
September	1st to 10th	Day	15% 3 6% 15% 33% 29%	2180
	11th to 20th	Day	18% 2 7% 27% 27% 19%	2090
	21st to end	Day	22% 2 4 24% 35% 13%	2090
October	1st to 10th	Day	21% 2 6% 19% 31% 21%	3458
	11th to 20th	Day	24% 2 6% 30% 33% 6%	3150
	21st to end	Day	28% 4 10% 34% 20% 5%	3141
November	1st to 10th	Day	39% 5% 12% 26% 15% 3	1701
	11th to 20th	Day	39% 4 17% 30% 9% 1	1710
	21st to end	Day	41% 3 16% 27% 12% 1	1669
December	1st to 10th	Day	46% 6% 18% 20% 7% 3	1520
	11th to 20th	Day	50% 3 26% 17% 4	1787
	21st to end	Day	46% 3 20% 19% 11%	2794
January	1st to 10th	Night	53% 5% 15% 23% 3 1	4406
	11th to 20th	Night	60% 4 17% 15% 3 1	4420
	21st to end	Night	52% 5% 20% 17% 5% 1	4633
February	1st to 10th	Night	49% 6% 17% 23% 5% 1	2470
	11th to 20th	Night	41% 4 18% 24% 12% 1	2268
	21st to end	Night	42% 5% 17% 26% 10% 1	1884
March	1st to 10th	Night	43% 6% 13% 25% 11% 2	3685
	11th to 20th	Night	31% 3 15% 31% 18% 1	3490
	21st to end	Night	43% 4 18% 28% 7% 1	3828
April	1st to 10th	Night	39% 4 11% 26% 15% 6%	1960
	11th to 20th	Night	36% 5% 10% 27% 20% 3	1739
	21st to end	Night	31% 3 11% 28% 25% 2	1710
May	1st to 10th	Night	36% 5% 8% 21% 23% 7%	2860
	11th to 20th	Night	20% 5% 7% 26% 32% 10%	2835
	21st to end	Night	28% 5% 11% 25% 29% 2	3053
June	1st to 10th	Night	26% 3 16% 28% 23% 4	1520
	11th to 20th	Night	23% 3 7% 22% 32% 13%	1520
	21st to end	Night	16% 2 4 15% 32% 32%	1520
July	1st to 10th	Night	11% 2 1 9% 20% 57%	2500
	11th to 20th	Night	13% 2 2 6% 19% 57%	2492
	21st to end	Night	18% 3 3 9% 28% 40%	2884
August	1st to 10th	Night	18% 3 3 13% 21% 42%	2838
	11th to 20th	Night	16% 3 2 14% 34% 31%	2838
	21st to end	Night	13% 3 2 12% 32% 38%	3233
September	1st to 10th	Night	14% 2 3 14% 32% 34%	1998
	11th to 20th	Night	19% 3 5% 22% 29% 22%	2090
	21st to end	Night	21% 2 3 20% 37% 17%	2090
October	1st to 10th	Night	18% 2 5% 15% 37% 24%	3521
	11th to 20th	Night	29% 3 5% 25% 30% 8%	3778
	21st to end	Night	28% 3 11% 33% 20% 5%	4413
November	1st to 10th	Night	37% 4 13% 23% 18% 4	2450
	11th to 20th	Night	38% 3 15% 28% 15% 1	2470
	21st to end	Night	36% 4 16% 31% 12% 1	2486
December	1st to 10th	Night	47% 4 19% 20% 7% 2	2660
	11th to 20th	Night	51% 4 19% 22% 4	3427
	21st to end	Night	48% 4 17% 20% 11%	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	17% 16% 22% 31% 14% 1	180
	11th to 20th	Day	12% 13% 21% 33% 14% 6%	180
	21st to end	Day	14% 10% 27% 25% 22% 1	265
February	1st to 10th	Day	21% 15% 30% 22% 12%	270
	11th to 20th	Day	15% 21% 32% 18% 13% 2	403
	21st to end	Day	15% 20% 30% 26% 8% 1	382
March	1st to 10th	Day	15% 18% 29% 26% 11%	460
	11th to 20th	Day	10% 15% 30% 27% 15% 2	460
	21st to end	Day	17% 21% 29% 23% 8% 2	506
April	1st to 10th	Day	16% 17% 28% 17% 14% 7%	460
	11th to 20th	Day	14% 19% 27% 23% 12% 4	452
	21st to end	Day	11% 17% 32% 20% 15% 5%	460
May	1st to 10th	Day	8% 17% 26% 27% 16% 5%	463
	11th to 20th	Day	13% 9% 25% 25% 20% 9%	488
	21st to end	Day	9% 10% 22% 23% 22% 14%	529
June	1st to 10th	Day	6% 9% 25% 26% 23% 11%	490
	11th to 20th	Day	8% 11% 31% 27% 19% 5%	490
	21st to end	Day	2 4 25% 35% 23% 11%	490
July	1st to 10th	Day	2 2 19% 34% 31% 11%	486
	11th to 20th	Day	2 2 20% 36% 31% 8%	484
	21st to end	Day	2 2 15% 34% 34% 13%	531
August	1st to 10th	Day	5% 2 20% 32% 29% 11%	487
	11th to 20th	Day	3 4 17% 29% 32% 15%	477
	21st to end	Day	3 5% 21% 24% 35% 14%	539
September	1st to 10th	Day	4 4 15% 29% 30% 18%	490
	11th to 20th	Day	5% 6% 19% 31% 26% 14%	490
	21st to end	Day	6% 8% 19% 29% 26% 12%	490
October	1st to 10th	Day	8% 7% 22% 26% 25% 12%	471
	11th to 20th	Day	7% 13% 19% 17% 32% 12%	300
	21st to end	Day	11% 9% 27% 29% 19% 5%	330
November	1st to 10th	Day	14% 14% 26% 23% 20% 3	279
	11th to 20th	Day	10% 10% 20% 34% 20% 5%	270
	21st to end	Day	14% 11% 17% 31% 23% 4	270
December	1st to 10th	Day	20% 9% 24% 27% 16% 4	270
	11th to 20th	Day	19% 16% 22% 27% 15% 3	198
	21st to end	Day	17% 16% 24% 27% 12% 4	198
January	1st to 10th	Night	14% 12% 22% 32% 19% 2	760
	11th to 20th	Night	13% 13% 19% 34% 19% 3	760
	21st to end	Night	16% 9% 18% 34% 21% 2	836
February	1st to 10th	Night	13% 11% 28% 32% 15% 1	760
	11th to 20th	Night	13% 9% 29% 33% 15% 1	744
	21st to end	Night	7% 13% 28% 36% 13% 1	628
March	1st to 10th	Night	9% 11% 26% 38% 14% 1	760
	11th to 20th	Night	8% 9% 25% 38% 19% 2	760
	21st to end	Night	12% 12% 28% 34% 14%	836
April	1st to 10th	Night	10% 13% 23% 36% 16% 2	760
	11th to 20th	Night	9% 13% 32% 32% 12% 2	611
	21st to end	Night	8% 10% 31% 33% 16% 2	570
May	1st to 10th	Night	8% 10% 27% 35% 19% 1	570
	11th to 20th	Night	7% 6% 21% 36% 26% 4	561
	21st to end	Night	13% 5% 19% 31% 27% 4	586
June	1st to 10th	Night	5% 6% 17% 43% 25% 3	380
	11th to 20th	Night	6% 7% 21% 46% 19% 1	380
	21st to end	Night	4 2 19% 46% 26% 4	380
July	1st to 10th	Night	2 1 11% 51% 33% 2	370
	11th to 20th	Night	1 1 12% 54% 31% 1	368
	21st to end	Night	1 1 10% 47% 38% 3	544
August	1st to 10th	Night	3 2 13% 48% 33% 2	567
	11th to 20th	Night	3 1 15% 46% 32% 3	564
	21st to end	Night	4 2 16% 44% 31% 3	675
September	1st to 10th	Night	3 2 14% 41% 35% 6%	760
	11th to 20th	Night	5% 2 15% 38% 33% 7%	760
	21st to end	Night	6% 3 17% 36% 28% 9%	760
October	1st to 10th	Night	8% 6% 18% 36% 29% 4	760
	11th to 20th	Night	9% 6% 19% 33% 29% 4	760
	21st to end	Night	8% 8% 22% 36% 24% 3	836
November	1st to 10th	Night	12% 8% 23% 32% 23% 3	754
	11th to 20th	Night	12% 9% 21% 38% 18% 2	760
	21st to end	Night	10% 8% 22% 33% 23% 4	776
December	1st to 10th	Night	15% 9% 24% 36% 16% 1	950
	11th to 20th	Night	17% 9% 18% 39% 15% 2	927
	21st to end	Night	19% 12% 24% 32% 11% 2	836

Page generated at 2024-11-01 20:47:29. Version ac07

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