Gillette
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gillette clear sky chart from 2005-11-06 to 2024-11-05.

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	7% 6% 2 5% 4 4 4 4 6% 8% 51%	105389
	Night	6% 7% 2 6% 4 4 4 4 6% 8% 49%	102386
Transparency	Day	30% 6% 12% 25% 19% 7%	105132
	Night	32% 6% 13% 26% 17% 5%	102233
Seeing	Day	10% 8% 29% 31% 17% 4	15901
	Night	10% 8% 35% 36% 11% 1	25895

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	2 6% 4 9% 6% 6% 5% 5% 7% 8% 42%	2538
	11th to 20th	Day	3 7% 4 8% 7% 6% 7% 4 6% 9% 41%	2540
	21st to end	Day	2 6% 3 7% 5% 4 4 3 5% 7% 54%	2956
February	1st to 10th	Day	6% 13% 7% 9% 6% 4 5% 4 6% 6% 34%	1710
	11th to 20th	Day	4 11% 4 10% 6% 5% 5% 3 5% 7% 39%	1706
	21st to end	Day	4 9% 5% 8% 6% 5% 5% 4 7% 6% 41%	1570
March	1st to 10th	Day	3 9% 2 6% 3 3 3 3 6% 7% 54%	3130
	11th to 20th	Day	6% 7% 2 5% 3 3 4 3 6% 9% 52%	3446
	21st to end	Day	12% 12% 3 9% 6% 4 4 4 6% 6% 35%	4054
April	1st to 10th	Day	9% 10% 3 6% 5% 5% 4 5% 6% 8% 41%	2280
	11th to 20th	Day	10% 12% 3 9% 5% 4 4 3 5% 6% 38%	2251
	21st to end	Day	14% 10% 2 5% 5% 4 4 4 6% 7% 39%	2327
May	1st to 10th	Day	15% 12% 3 6% 4 4 5% 4 6% 7% 35%	4430
	11th to 20th	Day	12% 7% 2 5% 3 4 4 4 6% 7% 47%	4388
	21st to end	Day	12% 7% 2 5% 4 4 4 4 6% 8% 44%	4825
June	1st to 10th	Day	7% 4 2 5% 3 4 4 5% 7% 10% 50%	2660
	11th to 20th	Day	8% 4 2 5% 4 4 4 4 7% 9% 49%	2660
	21st to end	Day	5% 2 1 3 2 3 4 4 6% 9% 61%	2660
July	1st to 10th	Day	4 2 1 3 3 4 4 4 7% 8% 59%	4430
	11th to 20th	Day	2 2 1 3 3 3 4 4 6% 9% 64%	4430
	21st to end	Day	3 2 1 3 3 3 4 3 7% 9% 62%	4802
August	1st to 10th	Day	8% 3 2 5% 3 4 4 4 7% 9% 50%	4297
	11th to 20th	Day	4 3 1 4 4 4 4 4 6% 8% 56%	3945
	21st to end	Day	2 2 1 2 2 3 3 3 5% 8% 70%	4180
September	1st to 10th	Day	6% 3 1 3 2 2 3 3 4 6% 66%	2280
	11th to 20th	Day	7% 4 1 4 3 2 4 3 5% 6% 60%	2280
	21st to end	Day	9% 4 1 4 3 3 3 2 4 5% 62%	2052
October	1st to 10th	Day	7% 4 1 3 2 2 2 2 3 4 69%	3170
	11th to 20th	Day	9% 5% 1 4 3 3 3 3 4 7% 59%	3150
	21st to end	Day	9% 7% 2 5% 3 4 4 3 5% 8% 49%	3191
November	1st to 10th	Day	7% 6% 3 5% 5% 3 4 4 6% 9% 48%	1709
	11th to 20th	Day	5% 9% 3 5% 4 4 4 4 7% 7% 47%	1582
	21st to end	Day	5% 9% 2 6% 4 4 4 4 5% 9% 48%	1520
December	1st to 10th	Day	4 9% 5% 9% 6% 5% 5% 4 5% 6% 42%	1520
	11th to 20th	Day	4 6% 3 6% 4 3 3 3 6% 8% 54%	1926
	21st to end	Day	3 8% 3 9% 5% 5% 5% 4 6% 6% 46%	2794
January	1st to 10th	Night	3 8% 4 9% 5% 4 5% 4 6% 8% 44%	4417
	11th to 20th	Night	3 7% 4 10% 7% 6% 5% 4 6% 7% 40%	4430
	21st to end	Night	3 7% 3 7% 5% 4 5% 4 7% 9% 48%	4741
February	1st to 10th	Night	4 12% 6% 12% 7% 6% 4 4 6% 7% 32%	2470
	11th to 20th	Night	3 12% 4 8% 5% 6% 5% 4 5% 8% 38%	2360
	21st to end	Night	3 10% 3 8% 6% 5% 5% 4 6% 8% 42%	1884
March	1st to 10th	Night	4 7% 3 7% 5% 4 4 4 6% 9% 48%	3734
	11th to 20th	Night	6% 7% 2 6% 4 4 4 4 5% 8% 50%	3531
	21st to end	Night	9% 9% 3 10% 6% 5% 4 4 7% 8% 34%	3590
April	1st to 10th	Night	11% 10% 3 5% 4 4 4 4 6% 7% 43%	1900
	11th to 20th	Night	11% 11% 3 8% 5% 4 6% 4 6% 6% 37%	1877
	21st to end	Night	11% 9% 2 5% 4 4 5% 4 7% 7% 41%	1846
May	1st to 10th	Night	15% 10% 3 5% 3 4 3 3 5% 6% 42%	2540
	11th to 20th	Night	10% 6% 2 4 3 4 4 5% 6% 8% 47%	2517
	21st to end	Night	14% 7% 2 6% 4 4 4 4 5% 8% 42%	2762
June	1st to 10th	Night	8% 5% 1 5% 4 4 4 3 9% 10% 46%	1520
	11th to 20th	Night	8% 3 2 5% 4 5% 5% 4 6% 8% 48%	1520
	21st to end	Night	5% 3 1 5% 2 2 4 3 5% 9% 61%	1520
July	1st to 10th	Night	4 4 1 3 4 3 4 4 7% 8% 58%	2540
	11th to 20th	Night	2 2 1 3 3 4 4 5% 8% 11% 57%	2540
	21st to end	Night	3 3 1 4 3 4 4 4 7% 9% 57%	2761
August	1st to 10th	Night	7% 4 1 4 4 4 4 4 6% 9% 52%	2640
	11th to 20th	Night	5% 3 1 5% 4 5% 5% 4 7% 9% 50%	2894
	21st to end	Night	3 2 1 4 3 3 4 4 6% 8% 62%	3487
September	1st to 10th	Night	7% 3 1 3 2 2 3 3 5% 7% 63%	1900
	11th to 20th	Night	7% 4 1 5% 3 3 4 3 7% 7% 56%	1900
	21st to end	Night	10% 4 1 4 3 3 3 2 4 6% 61%	2123
October	1st to 10th	Night	8% 5% 1 3 2 2 2 2 3 4 68%	3800
	11th to 20th	Night	10% 5% 2 4 3 3 3 3 5% 6% 56%	3778
	21st to end	Night	8% 7% 2 6% 3 4 3 3 5% 7% 52%	4336
November	1st to 10th	Night	7% 7% 3 6% 4 4 4 5% 6% 7% 47%	2470
	11th to 20th	Night	5% 10% 3 7% 5% 5% 4 4 6% 7% 44%	2594
	21st to end	Night	5% 7% 3 7% 4 5% 4 4 6% 8% 49%	2660
December	1st to 10th	Night	3 9% 4 10% 7% 5% 5% 4 6% 7% 41%	2660
	11th to 20th	Night	3 6% 3 6% 5% 5% 4 5% 6% 9% 48%	3271
	21st to end	Night	5% 10% 3 8% 5% 4 4 3 5% 7% 46%	4873

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	37% 8% 13% 29% 13%	2539
	11th to 20th	Day	38% 7% 16% 26% 9% 3	2540
	21st to end	Day	28% 6% 16% 33% 15% 2	2956
February	1st to 10th	Day	49% 6% 14% 19% 10% 1	1710
	11th to 20th	Day	44% 7% 12% 23% 11% 3	1715
	21st to end	Day	41% 6% 14% 23% 13% 4	1570
March	1st to 10th	Day	29% 4 11% 23% 27% 6%	3130
	11th to 20th	Day	29% 6% 21% 31% 12% 1	3446
	21st to end	Day	48% 8% 16% 22% 6%	4054
April	1st to 10th	Day	39% 7% 15% 25% 11% 3	2280
	11th to 20th	Day	46% 5% 13% 23% 12% 2	2254
	21st to end	Day	42% 6% 15% 24% 12% 1	2327
May	1st to 10th	Day	47% 6% 13% 22% 10% 3	4430
	11th to 20th	Day	34% 6% 12% 28% 18% 2	4392
	21st to end	Day	34% 8% 16% 29% 12% 1	4825
June	1st to 10th	Day	27% 9% 20% 27% 14% 3	2660
	11th to 20th	Day	28% 8% 15% 25% 18% 6%	2660
	21st to end	Day	19% 6% 13% 28% 24% 11%	2660
July	1st to 10th	Day	20% 6% 10% 29% 26% 9%	4361
	11th to 20th	Day	16% 4 8% 25% 31% 17%	4355
	21st to end	Day	17% 4 8% 21% 30% 19%	4651
August	1st to 10th	Day	28% 6% 12% 21% 20% 13%	4282
	11th to 20th	Day	24% 5% 9% 26% 28% 9%	3984
	21st to end	Day	13% 4 9% 24% 32% 18%	4179
September	1st to 10th	Day	19% 5% 6% 23% 32% 15%	2280
	11th to 20th	Day	24% 5% 7% 26% 26% 12%	2280
	21st to end	Day	25% 4 11% 30% 25% 6%	2052
October	1st to 10th	Day	22% 3 7% 18% 32% 19%	3170
	11th to 20th	Day	27% 4 11% 24% 28% 6%	3150
	21st to end	Day	33% 5% 13% 27% 18% 4	3191
November	1st to 10th	Day	32% 7% 14% 21% 21% 4	1709
	11th to 20th	Day	33% 6% 15% 26% 16% 4	1582
	21st to end	Day	33% 6% 14% 26% 18% 3	1520
December	1st to 10th	Day	41% 6% 13% 24% 14% 2	1520
	11th to 20th	Day	26% 6% 19% 33% 13% 2	1924
	21st to end	Day	37% 5% 9% 29% 14% 6%	2794
January	1st to 10th	Night	36% 7% 13% 33% 11% 1	4417
	11th to 20th	Night	40% 7% 16% 21% 12% 3	4430
	21st to end	Night	31% 8% 19% 29% 11% 2	4741
February	1st to 10th	Night	49% 7% 13% 18% 10% 3	2470
	11th to 20th	Night	43% 7% 14% 20% 13% 3	2361
	21st to end	Night	39% 6% 13% 21% 16% 5%	1884
March	1st to 10th	Night	30% 7% 13% 27% 21% 3	3734
	11th to 20th	Night	32% 6% 20% 25% 15% 2	3531
	21st to end	Night	44% 11% 19% 20% 6%	3590
April	1st to 10th	Night	38% 8% 14% 25% 11% 3	1900
	11th to 20th	Night	44% 8% 12% 24% 11% 1	1877
	21st to end	Night	39% 8% 14% 27% 11% 1	1846
May	1st to 10th	Night	42% 6% 15% 22% 15% 1	2540
	11th to 20th	Night	31% 8% 15% 32% 11% 3	2518
	21st to end	Night	38% 10% 15% 28% 8%	2762
June	1st to 10th	Night	28% 10% 24% 22% 15% 2	1520
	11th to 20th	Night	31% 8% 18% 23% 15% 5%	1520
	21st to end	Night	21% 6% 15% 27% 25% 7%	1520
July	1st to 10th	Night	21% 5% 11% 33% 23% 7%	2500
	11th to 20th	Night	18% 6% 12% 28% 27% 9%	2492
	21st to end	Night	22% 4 8% 26% 31% 8%	2674
August	1st to 10th	Night	27% 6% 14% 21% 20% 11%	2632
	11th to 20th	Night	28% 6% 13% 26% 20% 6%	2921
	21st to end	Night	20% 5% 10% 21% 28% 16%	3487
September	1st to 10th	Night	21% 3 8% 26% 28% 14%	1900
	11th to 20th	Night	26% 5% 10% 24% 24% 11%	1900
	21st to end	Night	26% 4 8% 27% 27% 8%	2123
October	1st to 10th	Night	23% 3 8% 22% 28% 16%	3800
	11th to 20th	Night	30% 4 8% 26% 28% 4	3778
	21st to end	Night	32% 4 11% 31% 14% 8%	4336
November	1st to 10th	Night	33% 6% 16% 23% 16% 6%	2470
	11th to 20th	Night	37% 5% 13% 25% 16% 4	2594
	21st to end	Night	31% 6% 15% 26% 19% 3	2660
December	1st to 10th	Night	40% 7% 13% 21% 16% 3	2660
	11th to 20th	Night	31% 7% 17% 32% 12% 1	3272
	21st to end	Night	38% 5% 10% 29% 15% 4	4873

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	6% 9% 32% 34% 15% 4	270
	11th to 20th	Day	10% 9% 41% 25% 11% 4	270
	21st to end	Day	8% 10% 46% 24% 9% 3	297
February	1st to 10th	Day	11% 12% 50% 22% 4	270
	11th to 20th	Day	9% 13% 40% 33% 5% 1	270
	21st to end	Day	5% 8% 40% 38% 8%	225
March	1st to 10th	Day	7% 13% 36% 34% 8% 2	270
	11th to 20th	Day	8% 11% 33% 31% 13% 2	429
	21st to end	Day	16% 14% 28% 27% 10% 4	506
April	1st to 10th	Day	17% 11% 33% 27% 10% 2	460
	11th to 20th	Day	13% 20% 32% 25% 10%	452
	21st to end	Day	18% 10% 25% 27% 17% 3	498
May	1st to 10th	Day	16% 13% 25% 26% 16% 5%	653
	11th to 20th	Day	18% 6% 25% 27% 19% 5%	675
	21st to end	Day	16% 9% 27% 27% 17% 4	734
June	1st to 10th	Day	6% 6% 27% 30% 24% 6%	680
	11th to 20th	Day	8% 12% 31% 32% 15% 3	680
	21st to end	Day	7% 5% 28% 36% 21% 4	680
July	1st to 10th	Day	4 3 20% 37% 30% 4	671
	11th to 20th	Day	3 3 23% 45% 22% 4	668
	21st to end	Day	4 2 23% 35% 30% 6%	739
August	1st to 10th	Day	5% 3 24% 37% 26% 5%	614
	11th to 20th	Day	6% 3 22% 33% 25% 10%	477
	21st to end	Day	3 5% 26% 33% 25% 8%	539
September	1st to 10th	Day	6% 4 23% 38% 20% 8%	490
	11th to 20th	Day	9% 6% 24% 31% 22% 8%	490
	21st to end	Day	11% 7% 25% 31% 18% 8%	305
October	1st to 10th	Day	15% 7% 21% 27% 17% 14%	300
	11th to 20th	Day	13% 8% 29% 30% 13% 6%	300
	21st to end	Day	11% 12% 33% 28% 14% 3	330
November	1st to 10th	Day	12% 10% 33% 31% 10% 5%	282
	11th to 20th	Day	9% 11% 41% 24% 13% 2	270
	21st to end	Day	11% 11% 39% 30% 8% 1	270
December	1st to 10th	Day	7% 13% 39% 32% 9% 1	270
	11th to 20th	Day	8% 14% 44% 26% 8%	270
	21st to end	Day	8% 16% 33% 29% 12% 1	297
January	1st to 10th	Night	9% 12% 37% 30% 11% 1	950
	11th to 20th	Night	8% 14% 43% 24% 9% 1	950
	21st to end	Night	10% 12% 41% 30% 7%	965
February	1st to 10th	Night	9% 12% 45% 27% 8% 1	760
	11th to 20th	Night	8% 10% 42% 33% 7% 1	744
	21st to end	Night	8% 11% 38% 34% 9% 1	628
March	1st to 10th	Night	7% 8% 41% 34% 9% 1	760
	11th to 20th	Night	9% 6% 38% 39% 8% 1	760
	21st to end	Night	13% 10% 32% 35% 10% 1	701
April	1st to 10th	Night	16% 9% 32% 35% 7%	570
	11th to 20th	Night	16% 12% 31% 34% 7% 1	563
	21st to end	Night	16% 8% 31% 34% 11%	570
May	1st to 10th	Night	14% 10% 25% 36% 15% 1	570
	11th to 20th	Night	17% 6% 25% 35% 16% 1	561
	21st to end	Night	16% 7% 31% 31% 14% 1	617
June	1st to 10th	Night	9% 8% 30% 39% 13% 1	570
	11th to 20th	Night	10% 8% 40% 34% 8%	570
	21st to end	Night	6% 5% 33% 45% 12%	570
July	1st to 10th	Night	6% 4 30% 45% 15%	555
	11th to 20th	Night	4 3 34% 48% 10%	552
	21st to end	Night	4 2 27% 52% 15%	624
August	1st to 10th	Night	5% 3 25% 50% 16% 1	567
	11th to 20th	Night	6% 4 23% 48% 18% 1	564
	21st to end	Night	5% 3 30% 44% 17% 1	627
September	1st to 10th	Night	8% 4 23% 48% 16% 1	570
	11th to 20th	Night	8% 5% 27% 39% 19% 1	570
	21st to end	Night	12% 5% 30% 37% 13% 2	608
October	1st to 10th	Night	16% 6% 27% 36% 13% 1	760
	11th to 20th	Night	14% 9% 29% 35% 11% 1	760
	21st to end	Night	11% 8% 35% 35% 11% 1	964
November	1st to 10th	Night	9% 8% 38% 34% 9% 1	950
	11th to 20th	Night	9% 12% 40% 31% 8% 1	950
	21st to end	Night	9% 9% 38% 36% 8%	950
December	1st to 10th	Night	6% 11% 43% 33% 7%	950
	11th to 20th	Night	7% 9% 43% 35% 6% 1	950
	21st to end	Night	11% 11% 41% 28% 8%	1045

Page generated at 2024-11-03 00:11:16. Version ac07

Copyright © 2024 Attilla Danko.