Bathurst
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bathurst clear sky chart from 2005-11-06 to 2025-04-11.

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	16% 9% 3 8% 5% 5% 5% 4 5% 6% 33%	113112
	Night	17% 10% 3 7% 5% 4 4 4 5% 6% 34%	115297
Transparency	Day	51% 5% 13% 20% 10% 1	116631
	Night	51% 6% 12% 20% 10% 1	119943
Seeing	Day	27% 17% 30% 18% 7% 2	16940
	Night	25% 16% 31% 21% 6% 1	24787

By Month

Percentage Cloud Cover NE (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	15% 17% 5% 12% 7% 5% 4 3 4 5% 23%	3157
	11th to 20th	Day	10% 13% 6% 13% 9% 7% 6% 4 5% 6% 22%	3195
	21st to end	Day	5% 6% 3 9% 5% 6% 6% 6% 6% 7% 42%	4205
February	1st to 10th	Day	9% 13% 4 8% 6% 6% 6% 4 7% 6% 32%	1800
	11th to 20th	Day	13% 14% 4 10% 6% 5% 5% 4 5% 5% 29%	1753
	21st to end	Day	10% 12% 4 9% 5% 5% 5% 3 5% 7% 35%	1525
March	1st to 10th	Day	20% 13% 4 7% 4 4 5% 4 4 6% 31%	4767
	11th to 20th	Day	15% 15% 5% 10% 6% 5% 5% 4 5% 6% 25%	4980
	21st to end	Day	22% 12% 4 8% 5% 4 4 3 4 6% 28%	5466
April	1st to 10th	Day	19% 12% 4 8% 6% 4 3 3 5% 6% 29%	2376
	11th to 20th	Day	19% 9% 2 6% 4 3 5% 3 5% 6% 37%	2442
	21st to end	Day	24% 10% 4 7% 4 4 3 3 5% 5% 30%	2470
May	1st to 10th	Day	20% 14% 4 8% 6% 5% 4 3 5% 6% 26%	4224
	11th to 20th	Day	19% 9% 3 7% 5% 4 4 3 6% 7% 33%	4398
	21st to end	Day	19% 8% 3 8% 6% 5% 5% 4 6% 7% 28%	5081
June	1st to 10th	Day	24% 8% 3 6% 4 4 4 3 6% 7% 31%	2850
	11th to 20th	Day	18% 7% 3 5% 5% 5% 5% 4 6% 7% 36%	2850
	21st to end	Day	24% 8% 3 7% 6% 6% 5% 4 6% 6% 26%	2850
July	1st to 10th	Day	14% 6% 3 8% 6% 6% 6% 5% 7% 8% 33%	4760
	11th to 20th	Day	12% 6% 2 7% 5% 6% 6% 5% 7% 8% 34%	4760
	21st to end	Day	12% 6% 2 6% 4 5% 5% 4 7% 9% 41%	4919
August	1st to 10th	Day	14% 7% 2 7% 5% 6% 6% 5% 7% 8% 33%	4105
	11th to 20th	Day	14% 5% 2 7% 6% 6% 6% 5% 7% 8% 34%	4045
	21st to end	Day	15% 5% 2 5% 4 4 4 4 5% 7% 44%	4532
September	1st to 10th	Day	15% 5% 2 7% 4 5% 4 3 6% 7% 42%	2284
	11th to 20th	Day	17% 5% 3 5% 4 4 4 3 4 5% 46%	2127
	21st to end	Day	18% 5% 2 6% 4 4 4 4 6% 7% 40%	2085
October	1st to 10th	Day	15% 6% 3 7% 5% 5% 4 3 5% 6% 42%	1900
	11th to 20th	Day	20% 8% 3 7% 4 4 5% 4 5% 6% 34%	1900
	21st to end	Day	23% 8% 3 6% 4 4 4 3 5% 6% 34%	1968
November	1st to 10th	Day	17% 10% 3 7% 5% 6% 5% 4 5% 7% 31%	1589
	11th to 20th	Day	22% 10% 3 7% 4 4 5% 3 5% 6% 31%	1600
	21st to end	Day	18% 13% 4 9% 4 4 5% 4 6% 6% 27%	1600
December	1st to 10th	Day	16% 12% 3 7% 4 5% 5% 3 5% 5% 34%	2455
	11th to 20th	Day	17% 11% 3 9% 6% 5% 5% 4 4 5% 31%	2618
	21st to end	Day	14% 13% 5% 8% 5% 5% 4 3 4 4 35%	3476
January	1st to 10th	Night	14% 16% 5% 10% 5% 5% 5% 4 5% 6% 24%	6808
	11th to 20th	Night	14% 12% 6% 10% 7% 5% 4 4 5% 6% 27%	6705
	21st to end	Night	6% 9% 3 7% 4 5% 5% 4 6% 7% 45%	6749
February	1st to 10th	Night	10% 14% 4 6% 5% 5% 5% 4 6% 8% 34%	2600
	11th to 20th	Night	14% 15% 4 8% 6% 5% 5% 3 5% 5% 31%	2533
	21st to end	Night	12% 14% 4 6% 5% 4 5% 5% 5% 5% 34%	2100
March	1st to 10th	Night	19% 13% 4 8% 5% 4 5% 3 4 5% 30%	5072
	11th to 20th	Night	21% 14% 4 8% 5% 5% 4 4 4 5% 25%	4979
	21st to end	Night	26% 12% 4 7% 4 4 3 3 4 6% 27%	5466
April	1st to 10th	Night	24% 11% 3 7% 4 4 3 3 4 5% 30%	2020
	11th to 20th	Night	22% 8% 3 7% 5% 4 4 4 5% 5% 34%	1695
	21st to end	Night	24% 12% 3 6% 4 3 3 3 4 6% 34%	1710
May	1st to 10th	Night	22% 10% 3 8% 5% 5% 4 3 5% 6% 29%	2718
	11th to 20th	Night	18% 7% 3 6% 4 4 4 4 6% 7% 36%	2506
	21st to end	Night	16% 9% 3 7% 6% 5% 6% 4 5% 8% 30%	2532
June	1st to 10th	Night	23% 10% 2 5% 4 3 6% 3 6% 5% 32%	1330
	11th to 20th	Night	18% 6% 2 5% 4 4 5% 5% 6% 7% 37%	1330
	21st to end	Night	23% 7% 3 7% 6% 6% 4 4 4 7% 30%	1330
July	1st to 10th	Night	12% 7% 3 7% 5% 5% 5% 4 6% 6% 40%	2210
	11th to 20th	Night	14% 6% 3 7% 4 5% 5% 5% 7% 7% 37%	2210
	21st to end	Night	10% 5% 2 6% 4 4 5% 4 6% 8% 46%	2604
August	1st to 10th	Night	16% 7% 3 8% 6% 6% 6% 4 6% 6% 31%	2825
	11th to 20th	Night	13% 7% 2 7% 5% 4 5% 5% 7% 8% 37%	2782
	21st to end	Night	13% 5% 2 6% 4 4 4 3 5% 7% 47%	3124
September	1st to 10th	Night	17% 5% 2 4 3 3 4 4 5% 7% 45%	1895
	11th to 20th	Night	14% 6% 2 6% 3 2 3 3 5% 8% 48%	2050
	21st to end	Night	17% 4 2 6% 3 4 3 3 5% 7% 46%	2095
October	1st to 10th	Night	20% 5% 2 6% 4 4 4 3 4 6% 42%	2280
	11th to 20th	Night	18% 8% 3 7% 5% 4 5% 3 5% 5% 39%	2280
	21st to end	Night	22% 9% 2 5% 4 4 4 3 6% 7% 35%	2627
November	1st to 10th	Night	20% 9% 3 7% 4 4 4 4 5% 6% 35%	2709
	11th to 20th	Night	20% 11% 4 8% 5% 4 4 3 5% 5% 31%	2800
	21st to end	Night	22% 11% 3 6% 4 5% 4 4 5% 6% 29%	2800
December	1st to 10th	Night	14% 10% 3 7% 5% 4 4 3 5% 6% 39%	4730
	11th to 20th	Night	17% 12% 3 7% 5% 5% 4 3 5% 5% 34%	5591
	21st to end	Night	17% 12% 4 10% 4 4 4 3 4 5% 32%	7502

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	65% 6% 11% 11% 7%	3158
	11th to 20th	Day	62% 7% 10% 13% 8%	3221
	21st to end	Day	40% 6% 11% 23% 19% 1	4205
February	1st to 10th	Day	50% 6% 12% 19% 11% 2	1800
	11th to 20th	Day	57% 5% 10% 17% 10% 1	1761
	21st to end	Day	50% 4 8% 24% 11% 3	1525
March	1st to 10th	Day	56% 5% 10% 16% 12% 2	4771
	11th to 20th	Day	60% 6% 12% 14% 7% 3	4980
	21st to end	Day	59% 2 6% 19% 12% 2	5466
April	1st to 10th	Day	57% 3 9% 17% 12% 2	2376
	11th to 20th	Day	48% 5% 12% 21% 14% 2	2442
	21st to end	Day	56% 5% 8% 15% 12% 4	2470
May	1st to 10th	Day	59% 5% 9% 18% 8% 1	4238
	11th to 20th	Day	49% 7% 15% 21% 8% 1	4402
	21st to end	Day	51% 8% 11% 19% 10%	5081
June	1st to 10th	Day	53% 6% 11% 19% 11%	2850
	11th to 20th	Day	47% 6% 13% 21% 11% 2	2850
	21st to end	Day	58% 6% 11% 16% 8%	2850
July	1st to 10th	Day	49% 4 16% 20% 10%	4685
	11th to 20th	Day	47% 5% 15% 26% 7%	4679
	21st to end	Day	40% 6% 21% 23% 10%	4761
August	1st to 10th	Day	48% 5% 17% 20% 9%	4092
	11th to 20th	Day	47% 5% 19% 21% 8%	4084
	21st to end	Day	41% 4 15% 24% 15% 1	4532
September	1st to 10th	Day	42% 6% 14% 25% 13%	2284
	11th to 20th	Day	41% 5% 13% 26% 14% 1	2127
	21st to end	Day	44% 6% 11% 26% 12% 1	2085
October	1st to 10th	Day	46% 3 14% 27% 9% 1	3160
	11th to 20th	Day	53% 4 11% 25% 8%	3140
	21st to end	Day	44% 4 15% 22% 14% 1	3218
November	1st to 10th	Day	53% 6% 10% 21% 9% 1	1589
	11th to 20th	Day	55% 7% 13% 14% 9% 1	1600
	21st to end	Day	58% 9% 13% 16% 5%	1600
December	1st to 10th	Day	56% 5% 11% 20% 8%	2455
	11th to 20th	Day	57% 5% 11% 17% 11% 1	2618
	21st to end	Day	54% 5% 11% 18% 9% 2	3476
January	1st to 10th	Night	61% 8% 13% 14% 4	6808
	11th to 20th	Night	59% 7% 11% 15% 8%	6754
	21st to end	Night	39% 5% 11% 25% 19% 1	6749
February	1st to 10th	Night	49% 5% 11% 18% 14% 2	2600
	11th to 20th	Night	55% 5% 10% 18% 11% 1	2536
	21st to end	Night	52% 4 9% 20% 12% 2	2100
March	1st to 10th	Night	59% 4 8% 15% 14% 1	5081
	11th to 20th	Night	61% 6% 10% 14% 9% 1	4980
	21st to end	Night	61% 3 5% 15% 14% 2	5466
April	1st to 10th	Night	57% 4 7% 15% 14% 3	2020
	11th to 20th	Night	51% 6% 8% 18% 14% 2	1695
	21st to end	Night	53% 5% 7% 17% 14% 3	1710
May	1st to 10th	Night	55% 7% 10% 16% 11% 1	2724
	11th to 20th	Night	44% 8% 14% 25% 8% 1	2507
	21st to end	Night	49% 10% 13% 20% 8% 1	2533
June	1st to 10th	Night	53% 7% 10% 19% 11% 1	1330
	11th to 20th	Night	44% 7% 13% 24% 11% 2	1330
	21st to end	Night	56% 6% 12% 17% 8% 1	1330
July	1st to 10th	Night	44% 5% 18% 22% 12%	2175
	11th to 20th	Night	46% 5% 15% 28% 6%	2168
	21st to end	Night	36% 8% 20% 26% 10%	2522
August	1st to 10th	Night	53% 6% 13% 21% 7%	2813
	11th to 20th	Night	45% 6% 20% 23% 6%	2809
	21st to end	Night	38% 4 17% 25% 15%	3124
September	1st to 10th	Night	39% 7% 12% 30% 11% 1	1895
	11th to 20th	Night	35% 5% 15% 30% 13% 1	2050
	21st to end	Night	39% 6% 12% 29% 13% 1	2095
October	1st to 10th	Night	50% 3 10% 28% 8% 1	3800
	11th to 20th	Night	47% 4 10% 30% 9%	3779
	21st to end	Night	45% 4 17% 22% 12%	4327
November	1st to 10th	Night	50% 7% 13% 21% 8% 1	2709
	11th to 20th	Night	55% 8% 11% 17% 8% 1	2800
	21st to end	Night	57% 9% 13% 15% 5% 1	2800
December	1st to 10th	Night	48% 5% 12% 25% 9%	4730
	11th to 20th	Night	53% 6% 9% 21% 10% 1	5592
	21st to end	Night	55% 5% 13% 19% 8% 1	7502

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	33% 19% 30% 16% 3 1	200
	11th to 20th	Day	34% 18% 24% 14% 9% 2	200
	21st to end	Day	21% 18% 36% 20% 4 1	322
February	1st to 10th	Day	25% 25% 27% 15% 5% 2	400
	11th to 20th	Day	26% 28% 28% 15% 3 1	396
	21st to end	Day	25% 21% 35% 16% 4 1	351
March	1st to 10th	Day	31% 17% 35% 14% 3 1	500
	11th to 20th	Day	28% 19% 29% 16% 6% 2	500
	21st to end	Day	31% 21% 29% 12% 6% 1	550
April	1st to 10th	Day	37% 20% 27% 12% 3 1	500
	11th to 20th	Day	29% 20% 29% 16% 5% 1	452
	21st to end	Day	35% 18% 25% 14% 4 2	460
May	1st to 10th	Day	32% 16% 28% 17% 6% 1	529
	11th to 20th	Day	28% 16% 27% 17% 11% 2	674
	21st to end	Day	29% 17% 31% 16% 6%	735
June	1st to 10th	Day	32% 13% 28% 19% 7% 2	680
	11th to 20th	Day	25% 16% 28% 21% 8% 2	680
	21st to end	Day	27% 15% 29% 21% 7% 1	680
July	1st to 10th	Day	19% 14% 32% 23% 10% 1	670
	11th to 20th	Day	14% 12% 36% 28% 8% 2	668
	21st to end	Day	20% 10% 31% 25% 11% 2	688
August	1st to 10th	Day	17% 14% 34% 24% 10% 1	486
	11th to 20th	Day	19% 10% 30% 28% 12% 1	479
	21st to end	Day	20% 10% 29% 26% 12% 3	539
September	1st to 10th	Day	17% 17% 33% 23% 8% 2	490
	11th to 20th	Day	23% 17% 29% 20% 8% 3	490
	21st to end	Day	25% 17% 30% 16% 8% 4	487
October	1st to 10th	Day	19% 19% 27% 21% 11% 4	390
	11th to 20th	Day	30% 19% 27% 14% 8% 2	390
	21st to end	Day	33% 23% 23% 14% 6% 1	429
November	1st to 10th	Day	31% 22% 29% 14% 4 1	395
	11th to 20th	Day	35% 19% 28% 14% 5% 1	400
	21st to end	Day	35% 20% 31% 12% 3 1	400
December	1st to 10th	Day	35% 15% 31% 15% 4 1	310
	11th to 20th	Day	32% 27% 28% 11% 2 1	200
	21st to end	Day	34% 18% 30% 15% 2	220
January	1st to 10th	Night	27% 19% 32% 17% 4	900
	11th to 20th	Night	27% 19% 33% 16% 5%	885
	21st to end	Night	20% 21% 35% 19% 4	880
February	1st to 10th	Night	21% 22% 32% 19% 5% 1	800
	11th to 20th	Night	30% 20% 31% 15% 4 1	783
	21st to end	Night	21% 17% 38% 17% 6%	660
March	1st to 10th	Night	27% 19% 33% 19% 3	800
	11th to 20th	Night	26% 15% 33% 18% 6% 1	800
	21st to end	Night	25% 18% 31% 20% 5% 1	880
April	1st to 10th	Night	32% 16% 30% 18% 4	655
	11th to 20th	Night	28% 15% 31% 18% 7%	567
	21st to end	Night	32% 14% 25% 22% 6% 1	570
May	1st to 10th	Night	27% 12% 28% 25% 7%	570
	11th to 20th	Night	24% 13% 30% 23% 9%	562
	21st to end	Night	22% 16% 34% 24% 5%	490
June	1st to 10th	Night	29% 9% 26% 29% 7%	380
	11th to 20th	Night	20% 10% 29% 31% 9% 1	380
	21st to end	Night	25% 9% 29% 28% 8% 1	380
July	1st to 10th	Night	18% 9% 35% 26% 10% 1	370
	11th to 20th	Night	13% 7% 37% 36% 7% 1	368
	21st to end	Night	16% 9% 31% 32% 12%	487
August	1st to 10th	Night	18% 7% 32% 33% 10%	568
	11th to 20th	Night	16% 9% 26% 36% 12%	562
	21st to end	Night	15% 9% 31% 31% 14% 1	627
September	1st to 10th	Night	19% 14% 33% 26% 8%	570
	11th to 20th	Night	20% 11% 30% 27% 11% 1	720
	21st to end	Night	21% 13% 32% 25% 10%	760
October	1st to 10th	Night	23% 15% 29% 22% 10% 1	760
	11th to 20th	Night	24% 17% 33% 18% 7%	760
	21st to end	Night	30% 20% 27% 19% 4	836
November	1st to 10th	Night	30% 19% 28% 17% 5%	867
	11th to 20th	Night	30% 19% 30% 14% 5% 2	900
	21st to end	Night	32% 18% 29% 16% 4	900
December	1st to 10th	Night	29% 18% 32% 16% 4	900
	11th to 20th	Night	32% 24% 29% 11% 4	900
	21st to end	Night	31% 20% 29% 17% 2 1	990

Page generated at 2025-04-08 10:17:25. Version ac07

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